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Principles  and  Practice   of 
Crowning  Teeth 


A  practical,  systematic  and  modern  treatise  upon  the     requirements     and     technique    of    artificial 
crown    work,    including    some    incidental    reference      to  bridgework. 


WITH  459  ILLUSTRATIONS. 


By 

HART  J.   GOSLEE,  D.D.S. 

Chicago.   III. 


JProfessor  Prosthetic   Dentistry   and   Crown   and  Bridgework,  Chicago  College  of  Dental  Surgery ; 
Dental   Surgeon   to  the  Attending   Staff,   Cook  County    Hospital;     Foreign    Associate    Member 
Society   of   Dentists   of   Norway;    Member   International   Dental   Federation;   National  Den- 
tal  Association;   Institute   of  Dental   Pedagogics;  Illinois  State  Dental  Society;  Chicago 
Dental   Society;   Odontographic  Society  of  Chicago:  Honorary  Member  South  Dakota 
Dental    Society;    Corresponding    Member    St.   Louis  Dental  Society,  etc.,  etc. 


New  York  : 

THE    CONSOLIDATED   DENTAL   MFG.  CO. 

London : 

CLAUDIUS  ASH  &  SONS  (LIMITED). 

1903. 


Copyright,  1903,  by  Hart  J.  Goslee. 
Entered  at  Stationers'  Hall,  London. 


TO    MY    FRIEXDS 

TRU.MAX    W.    BROPHY,   LL.D.,    -M.D.,  D.D.S. 

AND 

RODRIGUES   OTTOLEXGUI,   M.D.S.. 

In   recugnition   of   their   personal   and  professional   attainments,    and    as   a    small 

evidence    of    appreciation    of   their    friendship,   and   of  gratitude 

for  their  counsel  and  assistance 

THIS     BOOK     IS     RESPECTFULLY     INSCRIBED 
BY    THE    AUTHOR. 


Preface. 

The  development  of  the  specialty  of  crown  and  bridgework,  and  par- 
ticularly of  the  methods  of  crowning  teeth,  has  been  so  rapid  that  it  has 
probably  been  difficult,  if  not  indeed  quite  impossible,  for  the  average  prac- 
titioner to  keep  apace  with  the  numerous  modifications  of,  and  improve- 
ments in,  the  various  methods  of  procedure  which  have  been  constantly 
presented  and  advocated  in  the  evolution  of  this  specialty  from  a  some- 
what chaotic,  and  at  best  unsystematic  beginning,  to  its  present  acknow- 
ledged position  as  a  distinct  and  highly  artistic  and  practical  department 
of  dental  prosthesis. 

It  is  therefore  believed  that  there  is  a  need  at  the  present  time  for 
a  strictly  modern  text  and  reference  book,  embracing  a  tangible,  syste- 
matic and  practical  classification  of  the  subject,  supplemented  with  ade- 
quate illustrations. 

In  assuming  to  supply  such  a  possible  need  an  effort  has  been  made 
to  present  the  subject  matter  in  a  practical  and  concise  form,  and  in  a 
more  or  less  systematic  and  sequential  order ;  as  well  as  to  avoid,  in  so 
far  as  possible,  any  consideration  of  methods  which  may  have  proven,  or 
which  are  deemed,  to  be  impracticable ;  or  those  which  may  have  been 
abandoned,  or  have  become  obsolete. 

Special  care  has  been  given  to  the  presentation  of  the  various  methods 
which  are  practiced,  and  which  are  recognized  as  possessing  merit  and 
practicability.  This  is  deemed  warrantable,  and  indeed  essential,  for  the 
reason  that  in  the  successful  practice  of  a  specialty  in  which  a  very  high 
order  of  art  and  mechanics  is  demanded,  and  which  involves  more  or  less 
permanent  application  as  a  part  of  the  human  economy,  where  the  con- 
ditions presenting  are  so  greatly  diversified,  there  is  no  one  best  method. 
Some  procedures  will  be  found  more  applicable  to  one  case  than  to 
another,  and  to  be  more  practical  and  successful  in  some  hands  than  in 
others. 

Personal  equation  and  good  judgment  will  dictate  and  enter  largely 
into,  the  application  of  the  most  practical  method  to  be  pursued  in  each 
case,  and  this  will  usually  have  as  much  bearing  upon  the  success  and 
serviceability  of  the  operation  contemplated,  as  will  the  degree  of  skill 
which  may  be  exhibited  in  the  execution  of  the  details  of  construction. 


The  various  methods  and  techni(|ue  of  modern  procedures  are  pre- 
sented and  commented  upon  fr.jm  an  original  and  unl^ased  viewpoint. 
This  is  done  with  the  belief  that  their  respective  application  and  practic- 
ability will  thus  probably  be  more  logically  elucidated;  and  that  their 
merits  will  be  less  likely  to  be  overestimated,  than  if  they  were  presented 
in  the  language  of  the  original  advocate,  because  of  the  enthusiasm  which 
would  thus  naturally  tincture  the  claims  made  for  them. 

In  so  far  as  possible  every  effort  has  also  been  made  to  acknowledge 
and  give  due  credit  as  to  the  origin  of  the  many  valuable  and  ingenious 
ideas  and  suggestions  which  have  aided  so  much  in  the  development  of 
this  class  of  work,  and  in  placing  this  specialty  upon  a  somewhat  sound, 
systematic  and  practical  basis  ;  as  well  as  to  those  which  have  served  to 
facilitate  and  expedite  the  procedure  and  to  relieve  the  patient  of  any 
unwarranted  or  unnecessary  discomfiture  incident  to  the  operation. 

Where  several  similar  methods  of  detail  are  mentioned  in  connection 
with  a  single  mode  of  procedure,  they  are  invariably  placed  in  the  order 
of  their  preference,  unless  otherwise  emphasized  in  the  text. 

All  reference  to  the  therapeutic,  or  surgical  technique  possibly  indi- 
cated in  the  treatment  of  pathological  conditions  involving  the  roots  of 
teeth,  or  surrounding  tissues,  has  been  purposely  avoided,  in  the  belief 
that  such  matter  more  properly  belongs  to  works  on  therapeutics  per  se, 
rather  than  to  a  book  which  is  designed  only  as  a  practical,  and  compre- 
hensive elucidation  of  the  principles,  practice  and  technique  of  modern 
methods  of  crowning  teeth. 

Hart  J.  Goslee. 
Chicago,  111.,  April  30th.  1903. 


Principles  and  Practice  of  Crowning  Ceetb. 


fiistory  and  Development  of  grown  morK. 


CHAPTER    I. 

Primitive   Application   of  Crowns.     First   Application    of    Porcelain    Crowns.      The 

Use    of   English    Tube-Teeth    for    Crowns.      The    Foster    Crown.      The    Mack 

Crown.     The  Shell  or  Telescope  Crown.      The   Gates-Bonwill   Crown.     The 

Howland-Perry   Crown.     The   Richmond  Crown.     The   Biittner  Crown. 

The  How  Crown.     The  Weston  Crown.     The  Logan  Crown.     The 

Brown  Crown.    The  Webb  Crown.    Application  of  Porcelain  to 

Crown  Work.     Various  Modifications  of  These  Principles. 


While  dental  literature  as  early  as  the  beginning  of  the  eighteenth 
centtiry  records  instances  of  the  application  of  pivot  teeth  to  roots,  the 
practical  introduction  of  artificial  substitutes  for  the  natural  crowns  of 
teeth  lost  through  accident,  or  by  the  process  of  caries,  and  the  ultimate 
development  of  crown  and  bridgework  is  purely  the  product  of  the  last 
half  of  the  nineteenth  century,  and  must  be  placed  to  the  credit  of  Ameri- 
can dentistry. 

As  the  profession  itself  has  from  humble  environments  grown  and 
broadened  into  a  scientific  calling  with  marvelous  rapidity,  so  also  has 
the  specialty  of  crown  and  bridgework,  the  evolution  of  the  application 
and  construction  of  which  forms  an  interesting  chapter  in  any  history  of 
the  conception,  progress  and  advancement  of  all  that  pertains  to  dental 
art  and  prosthesis. 

Besides  opening  new  fields  for  higher  artistic  conceptions,  it  has 
also  materially  aflected  the  general  advancement  of  the  profession,  for 
at  one  time  it  seemed  propitious  and  apparently  inevitable  that  the  lattef 


should  become  divided  into  the  separate  branches  of  operative  and  me- 
chanical dentistry,  and  that  it  would  be  the  exception  rather  than  the  rule 
for  the  average  person  to  attain  a  degree  of  proficiency  in  both  branches  so 
dissimilar  to  one  another. 

This  specialty,  however,  then  just  budding  into  general  favor  by  the 
recognition  of  its  possibilities,  and  so  equally  dividing  the  labor  involved 
between  the  mind  and  the  hand,  the  chair  and  the  laboratory,  soon 
proved  the  fallacy  of  such  thoughts,  and  resulted  in  reuniting  these 
branches,  thus  greatly  encouraging  the  unprecedented  advance  which 
the  profession  has  since  made. 

To  crown  and  bridgework  also  can  be  attributed  much  of  this 
progress,  for  no  field  in  art  or  mechanics  offers  greater  opportunity  for  the 
display  of  individual  skill  and  artistic  attainments. 

The  employment  of  these  talents  in  any  line  cultivates  the  finer  in- 
stincts, promotes  a  higher  sense  of  appreciation  of  nature,  and  draws  a 


Ficj.l.  Fiq.2. 

fine  line  of  distinction  between  the  tradesman  or  artisan  and  the  true 
artist;  and,  in  the  province  of  dentistry,  enables  one  to  more  nearly  imi- 
tate, and  often  improve  upon,  the  normal  or  abnormal  conditions  which 
lend  so  much  to  the  appearance  and  comfort  of  those  who  might  other- 
wise be  prematurely  disfigured  or  permanently  subjected  to  discomfiture. 

From  available  records  the  first  application  of 
Primitive  Jlpplicatlon   "pivot  teeth"  is  described  in  Fauchard's  work,  pub- 
Of  0rowits,  lished  in  1728,  in  which  mention  is  made  of  a  crown 

fastened  to  the  root  with  a  pivot,  and  which  con- 
sisted of  a  crown  carved  out  of  bone  or  ivory,  or  one  of  a  natural  tooth, 
mounted  upon  the  root  with  a  roughened  pivot  of  silver  or  gold.  The 
interior  of  the  root  was  first  filled  with  lead,  into  the  center  of  which  a 
hole  was  aftervvard  drilled  for  the  reception  of  the  pivot,  the  other  end  of 
which  had  been  previously  cemented  in  a  hole  in  the  crown.     Fig.  i. 

In  the  work  of  de  Chemant,  published  in  1816, 
nearly  one  hundred  years  later,  much  reference  is 
made  to  the  use  of  "mineral  paste,"  and  a  brief  de- 
scription is  given  of  "a  single  tooth  with  pivot,"  ac- 
companied with  a  crude  illustration,  which  indicates 
that  it  was  intended  as  a  crown  to  be  attached  to  a  root.     Fisr.  2. 


first  Application 

of 
Porcelain  Crowns, 


While  other  designs  of  "mineral"  teeth  were  subsequently  recordec 
in  French  literature,  in  which  country  porcelain  was  first  apphed,  it  was 
not  until  about  1S40  that  much  effort  was  made  toward  the  preservation 
of  broken-down  roots,  or  much  thought  given  to  the  problem  of  restor- 
ing lost  crowns  of  teeth,  the  prevailing  and  common  practice  having 
been  to  extract  them  and  insert  plates ;  or,  in  some  instances,  to  grind 
them  down  even  with  the  tissues  and  retain  them  for  the  purpose  of 
preventing  alveolar  absorption. 

About  this  time  more  progressive  and  esthetic 
€ndli$b  ideas   were   conceived   which   resulted   in   the  intro- 

tUbC  C««tl).  duction  and  first  practical  application  in  this  country 

of  artificial  crowns,  in  the  form  of  the  English  tube- 
teeth,  designed  and  previously  used  for  plate  work ;  they  were  ground  to 
fit  the  root  and  mounted  with  pivots  of  hickory  wood.  This  was  con- 
ceded to  be  a  marked  step  in  advance — a  revelation  indeed — and  proved 


r/7.4. 


the  formative  period  of  that  class  of  work  which  was  destined  to  develop 
into  such  an  important  specialty.  But  the  theory  of  the  wooden  pivot 
serving  as  a  means  of  anchorage  by  virtue  of  the  expansion  incident  to 
the  absorption  of  moisture  soon  proved  impracticable,  because  of  the  in- 
adequate stability,  and  not  infrequent  occurrence  of  fractured  roots  as  a 
result  of  the  swelling  of  the  wood,  as  well  as  the  necessary  presence  of 
moisture  which  induced  decay.    Fig.  3. 

Some  modifications  of  this  method  are  recorded  whereby  effort  was 
made  to  overcome  the  objectionable  features  and  permit  of  the  removal 
of  the  crown  in  order  to  facilitate  the  treatment  of  the  roots,  which  devel- 
oped into  a  necessity  as  the  result  of  sealing  them  up  without  proper 
aseptic  considerations. 

The  most  prominent  of  these  were  the  crown  attachment  patented  in 
1844  by  Dr.  J.  S.  Dodge,  which  consisted  of  mounting  a  wooden  tube 
into  the  root  and  attaching  a  metal  dowel  to  the  crown  with  plastics,  which 
fitted  closely  into  the  cylinder  of  wood,  yet  rendered  its  removal  easy; 
and  the  design  of  Dr.  F.  H.  Clark,  patented  in  1849  and  comprising  the 
insertion  of  a  metal  tube  in  the  root  which  was  anchored  securely  with  a 


4 

large-headed  screw-pivot,  perforated  through  the  center  to  allow  accu- 
mulated gases  to  escape.  To  the  projecting  or  free  end  the  crown  was 
attached. 

Because   of  the   tendency   of  these   crowns    to 
Cl)c  loosen  in  their  attachment  to  the  pivot,  and  the  ob- 

fOStcr  €rown.  jections  to  wooden  pivots,  the  Foster  crown  was  pat- 
tented  in  1855,  and  while  constructed  upon  almost 
the  same  lines  as  one  designed  some  five  years  preceding  it,  by  Dr. 
Henry  Lawrence,  it  enjoyed  quite  an  extensive  use  for  a  number  of  years 
under  the  former  name.  It  possessed  almost  a  flat  base,  with  a  perfora- 
tion in  the  body  of  the  porcelain  so  shaped  as  to  form  a  seat  for  the  ac- 
commodation of  the  enlarged  head  of  a  screw-pivot,  by  which  means  it 
was  anchored  securely  to  the  root.     Fig.  4. 


Fic^ 


5, 


F!j.  6. 


While  in  the  former  styles  the  dowel  was  first 
Cl)i  JIlacR  Crown.  attached  to  the  crown  and  then  subsequently  to  the 
root,  the  design  of  Dr.  C.  H.  Mack,  patented  in 
1872,  is  recorded  as  the  first  instance  where  the  dowel  was  attached  firmly 
in  the  root  before  the  crown  was  fixed  in  place  upon  it.  The  crown  was 
constructed  with  a  countersunk  cavity  in  the  body  of  the  porcelain  which, 
being  filled  with  plastics,  anchored  it  securely  when  mounted.     Fig.  5. 

The  difficulty   experienced  in   adapting  any  of 
CbC  Shell  the  former  styles  to  the  posterior  teeth  in  a  practical 

or  or  permanent  manner,  and  the  desirability  of  restor- 

Celescopt  Crown.       ing    and    preserving    their    normal    functions,    ulti- 
mately led  to  the  invention  of  the  gold  shell  or  tele- 
scope crown,  patented  by  Dr.  J.  B.  Beers  in  1873.  though  probably  first 
suggested  by  Dr.  W.  N.  Morrison  some  few  years  previously. 

This  crown  proved  a  great  step  in  the  line  of  progress  and  develop- 
ment, because  the  construction  did  not  require  the  sacrificing  of  tooth 


structure  to  the  extent  necessary  for  porcelain  crowns,  and  made  pos- 
silile  the  better  and  more  serviceable  reproduction  of  natural  tooth  forms. 
The  seam  of  union  between  crown  and  root  was  for  the  first  time  carried 
under  or  within  the  free  margin  of  the  gum  and  apparently  made  the 
operation  a  more  permanent  success  than  had  theretofore  seemed  pos- 
sible.    Fig.  6. 

The  success  and  practicability  of  this  style  of  crown  has  resulted  in 
the  subsequent  invention  from  time  to  time  of  innumerable  systems  and 
methods  of  construction,  all  of  which  while  varying  in  detail  accomplish 
practically  the  same  end;  and,  while  it  has  done  much  to  prove  the  ad- 
visability of  encompassing  the  end  of  the  root  with  a  band,  and  to  a  great 
extent  made  possible  the  ultimate  success  of  permanent  stationary 
bridgework,  its  virtues  have  been  most  grossly  abused  in  their  applica- 
tion to  anterior  teeth,  and  through  their  production  in  ready-made  form-, 
the  use  of  which,  in  justice  to  the  artistic  possibilities  within  the  reach  of 
the  modern  dentist,  cannot  be  too  vigorously  condemned. 


Ficj .  7. 


Ficj.  8. 


As  the  result  of  the  more  or  less  successful  ex- 

Cbc  periment  with  the  Foster  and  Mack  crowns,  an  im- 

GatCS-Bonwill  CroU'll.    provement    subsequently    appeared    in    a    tooth    that 

became  known  as  the  Gates-Bonwill  crown,  a  patent 

having  been  issued  to  Dr.  W.  H.  Gates  in  1875,  and  to  Dr.  W.  G.  A. 

Bonwill  in  1881,  covering  practically  the  same  ideas. 

This  crown  was  of  porcelain,  constructed  with  a  concave  instead  of 
a  flat  base,  and  having  a  triangular  perforation  through  the  body  of  the 
porcelain,  afiforded  a  better  and  more  secure  means  of  attachment  to  the 
root,  to  which  it  was  secured  by  means  of  a  metal  dowel  which  was 
threaded  and  screwed  into  the  canal,  after  which  the  crown  was  anchored 
with  amalgam.     Fig.  7. 

Shortly  after  this  the  Rowland  crown,   subse- 

CbC  1)0Wland-         quently  modified  by  Dr.  S.  G.  Perry,  and  styled  the 

PCffy  0rOWIt.         Howland-Perry  crown,   was   suggested.     This   was 

very  similar  to  the  preceding  ones,  but  differed,  like 

the  Mack  crown,  in  that  the  accommodation  for  the  dowel  was  confined 

to  a  cavity    in  the    body  of    the  porcelain,    instead  of    passing  entirely 

through    it.      This    followed    the    then   developing   tendency    toward   the 


esthetic,  by  the  preservation  of  the  continuity  of  the  exposed  surfaces  of 
porcelain,  not  disclosing  the  end  of  the  metal  dowel  or  the  mounting 
material.    Fig.  8, 

This  design  was  patented  by  Dr.   C.   M.  Rich- 

tftC  mond  in  1880,  and  consisted  of  a  cap  encompassing 

KiCbltlOnd  €rOWn.       the  end  of  the  root,  to  which  a  facing  similar  to  the 

ordinary  plate  tooth  was  attached  by  soldering.   This 

was  the  first  practical  application  of  a  band  to  a  root  for  anterior  crowns 

with  porcelain  facings. 

As  originally  designed,  it  consisted  of  a  band,  to  which  was  soldered 
a  floor,  forming  a  cap.  To  this  was  then  attached  a  facing  hollowed  out 
between  the  pins  so  as  to  accommodate  a  threaded  dowel  which,  passing 


Fiq  .10. 


•through  the  cap,  was  then  screwed  into  a  tube  previously  mounted  in  the 
■canal,  thus  attaching  the  crown  to  the  root.     Fig.  9. 

While  it  was  then  for  some  time  a  matter  of  doubt  and  conjecture 
as  to  the  advisability  of  banding  the  anterior  teeth,  and  as  to  whether  it 
was  an  objectionable  or  an  advantageous  procedure,  the  original  prin- 
ciple was  soon  abandoned  because  of  the  intricate  and  unstable  manner 
of  attachment,  and  the  apparent  uselessness  of  a  separate  dowel,  but  the 
modifications  and  improvements  resulting  from  this  suggestion  are  now 
conceded  to  be  the  best  means  of  securing  permanence  in  the  operation, 
.and  are  the  accepted  practice  of  today. 

During  the  early  agitation  of  the  feasibility  of 
the  banding.  Dr.  H.  W.  Biittner  invented  a  metal  and 

Biittnef  0rown.        porcelain   crown   with   a   band   wherein  the   method 
employed  in  attaching  it  to  the  root  would  possess 
the  advantages  of  a  band,  and  at  the  same  time  preclude  its  possible  irri- 
tating influences. 


This  was  accomplished  by  trephining  the  periphery  of  the  end  of 
the  root  to  form  suitable  accommodation  for  the  band,  with  instruments 
specially  devised  for  the  purpose,  but  the  idea  never  met  with  universal 
favor,  and  it  was  soon  abandoned.    Fig.  lo. 

A  crown  devised  by  Dr.  W.  S.  How  in  1883 
thi  Bow  Crown.  consisted  of  a  thin  facing  with  four  pins  and  a  slotted 
back  for  the  reception  of  the  "screw-post,"  whicli 
was  anchored  to  the  facing  by  bending  the  pins  over  it  after  it  was  backed 
up,  and  the  desired  contour  was  then  built  up  with  solder.  The  extreme 
thinness  and  consequent  weakness  of  the  porcelain  rendered  its  usefulness 
limited.     Fig.  11. 


F'(f  .11. 


Fiq.lS. 


Fiq.13. 


Another    similar    form    was    invented    by    Dr. 

tbC  Henry  Weston  in  1883  and  subsequently  modified. 

Uleston  Crown.        The  first  design  comprised  a  means  of  attaching  the 

dowel  to  the  facing,  which  is  best  described  by  the 

illustration,  after  which  it  was  attached  to  the  root.    Fig.  12. 

In  the  modification  the  dowel  was  first  securely  fixed  in  the  root  and 
then  the  crown  which  was  constructed  with  a  view  of  being  much 
stronger,  was  held  in  contact  with  the  root,  and  anchored  by  packing 
through  an  opening  for  the  purpose,  on  the  lingual  surface.    Fig.  13. 

It  will  be  observed  that  up  to  this  time  the  various  steps  in  the  de- 
velopment of  the  work  consisted  of  a  crown  and  dowel  as  two  separate 
parts,  but  here  a  deviation  in  the  principle  was  made  for  the  purpose  of 
securing  additional  strength,  in  which  the  dowel  became  an  integral  part 
of  the  crown  by  being  baked  in  the  body  of  the  porcelain. 

This  crown,  the  first  to  be  so  constructed,  was 

Z\it  Cogan  Crown,     the  invention  of  Dr.  M.  L.  Logan,  patented  in  1885, 

and  made  with  a  large  body  of  porcelain  having  a 

concave  countersunk  base  to  facilitate  adaptation  to  root,  and  a  dowel 

shaped  more  in  line  with  scientific  principles.    More  nearly  approaching 


the  requirements  in  conformation  than  any  of  its  predecessors,  it  soon 
became  very  popular,  eventually  supplanting  all  other  designs  of  similar 
nature,  and  for  years  has  had  an  extensive  use  and  appHcation.    Fig.  14. 

Another  design  was  shortly  afterward  evolved 

tbe  Brown  (Krown.     and  introduced  by  Dr.  E.  Parmley  Brown,  and  while 

of  the  same  type,  it  possessed  a  base  convex,  instead 

of  concave,  with  a  view  of  affording  by  means  of  its  construction,  the 

greatest   possible   strength   at  the   seam   of   union   between  crown   and 

dowel,  and  crown  and  root. 

Its  adaptation  to  the  root  after  cutting  it  down  properly  was  made 
by  using  a  bur  which  produced  a  concavity,  to  accommodate  the  con- 
vexity of  the  base  of  the  crown ;  but  the  increased  strength  of  the  crown 
being  secured  at  the  expense  of  the  root,  soon  resulted  in  its  abandon- 
ment.   Fig.  15. 


Fiq.14.. 


^iQ .  15. 


f^'cj .  16. 


The  difficulty  of  grinding  one  surface  to  closely 
Cbe  mcbb  €fOWn.  approximate  another,  and  the  conceded  advantages 
of  a  close  union  between  crown  and  root,  soon  stim- 
ulated a  desire  to  secure  better  adaptation,  and  resulted  in  the  sugges- 
tion of  a  plate  and  dowel  crown  probably  first  used  by  Dr.  M.  H.  Webb. 

This  was  constructed  by  swaging  or  burnishing  a  metal  plate  to 
the  end  of  the  root,  then  perforating  it  to  admit  of  inserting  into  the 
canal  a  dowel,  which  was  soldered  to  the  plate,  to  which  the  facing  was 
then  attached.  The  possibilities  of  adaptation  and  its  advantages  have 
become  so  recognized  that  many  still  so  construct  their  crowns,  and 
they  are  frequently  indicated.    Fig.  16. 

Soon,  however,  the  advancement  of  the  profession  along  those  lines 
leading  to  the  achievement  of  the  very  highest  conceptions  of  art,  indi- 
cated a  tendency  to  observe  the  maxim  "true  art  is  to  conceal  art,"  and 
created  a  desire  for  something  that  might  supersede  the  use  and  display 
of  gold,  something  more  nearly  resembling  and  harmonizing  with  nature, 
yet,  still  serving  the  same  purposes.  Even  in  this  the  inventive  genius 
of  the  profession  was  not  long  in  again  asserting  itself,  and  soon  after- 
ward came  the  application  of  vitrified  porcelain. 


The  first  suggestions  were  perhaps  made  Ijy  Ur.  C.  H.  Land,  and  were 
eagerly  studied  and  enthusiastically  applied  with  varying  degrees  of  success 
and  failure.  Dentures  of  platinum  and  porcelain  had  been  constructed  and 
worn  successfully  for  years,  hence  it  was  readily  believed  that  crowns 
and  bridges  of  the  same  must  also  of  necessity  be  equally  successful. 
In  this,  however,  many  were  doomed  to  disappointment,  and  because 
of  inadequate  knowledge  of  the  requirements,  too  much  confidence,  and 
the  over-zealous  enthusiasm  of  early  advocates,  its  use  and  practicability 
soon  became  questionable,  and  was  eventually  discontinued  by  the  great 
majority. 

There  were  those,  however,  who,  still  admiring  its  esthetic  beauties, 
and  having  faith  in  its  possibilities,  sought  to  ascertain  the  causes 
of  failures,  and  the  reasons  for  success,  with  the  result  that  its  more 
recent  and  modern  application  has  approached  and  made  possible  the 
very  highest  degree  of  perfection  in  dental  art  and  prosthesis.  Yet  it  is 
not  universally  applicable,  and  will  never  supersede  the  use  of  gold. 
The  success  of  each  must  always  depend  in  a  great  measure  upon  the 
sound  reasoning,  good  judgment  and  skilful  execution  and  discrim- 
ination with  which  they  are  respectively  applied. 

It  will  be  observed  that,  from  the  very  beginning,  the  innate  and 
intuitive  desire  for  the  practical  and  esthetic  development  of  this  work 
to  more  perfectly  meet  the  demands  and  requirements  of  the  times,  has 
resulted  in  the  presentation  of  many  varied  principles  and  methods,  among 
which  may  be  also  included  the  jacket  crowns;  the  application  of  por- 
celain facings  to  shell  or  telescope  crowns;  the  Logan  crown  with  the 
addition  of  a  band;  the  various  modifications  of  the  porcelain  crown 
with  separate  dowel,  such  as  the  Davis  crown,  the  intradental  band 
and  similar  designs,  and  a  galaxy  of  other  varying  and  ingenious 
ideas.  Yet  they  are  in  the  main  but  modifications  of  the  original  prin- 
ciples enumerated,  and,  while  aiding  materially  in  the  evolution,  and 
showing  the  trend  of  the  development  and  progress  of  crown  work  from 
its  inception,  their  individual  description  would  be  redundant  and 
unnecessary.  v 

Those  of  practical  value,  use  and  application  at  the  present  time  can 
be  treated  to  better  advantage  elsewhere  than  in  a  breif  resume  of  the 
development  and  history  of  this  work,  which  is  intended  only  to  show 
the  perseverance  and  ingenuity  of  our  predecessors,  and  the  various 
steps  in  making  possible  the  success  of  modern  crown  work,  for  which 
their  efforts  were  primarily  responsible. 


metals,  jFfiioys  and  Solders. 


CHAPTER    II. 

Symbol  and  Fusing  Point  of  Metals  Used.     Noble  and  Base  Metals.     Chemical  and 

Physical  Properties  :    Chemical   Action,  Color,  Odor   and   Taste,  Fusibility, 

Malleability,    Ductility,    Tenacity.     Physical    Processes  :    Soldering, 

Welding,  Annealing,    Tempering,    Alloying,    Troy  Weight. 

Consideration  of   the    Metals  :   Gold,   Karat,   Platinum,  Iridium.     Alloys  :  Alloys   of 

Gold,  Coin  Gold,   Gold  and  Platinum,   Platinized  Gold.     Solders  :    Platinum 

Solder,  Gold  Solders,  Compounding  Solders,  Brass,  Dorrance's  Alloy, 

Silver  Solder,   German   Silver,  Fusible  Alloys,  Soft  Solder, 

Refining  Gold,   Etc. 


One  of  the  first  essential  duties  incident  to  the  successful  execu- 
tion of  any  Hne  of  work  in  art  or  mechanics  is  a  thorough  practical 
knowledge  of  the  materials  used;  hence,  in  the  construction  and  appli- 
cation of  crown  and  bridge  work,  wherein  the  use  and  manipulation 
of  the  metals  and  their  combinations  forms  such  an  important  feature, 
it  is  materially  necessary  that  the  dentist  should  be  acquainted  with 
their  characteristics,  physical  properties  and  methods  of  manipulation. 

This  is  imperative  only  that  he  may  the  better  understand  their 
appHcation,  for  it  no  longer  becomes  necessary  for  him  to  be  an  expert 
metallurgist,  to  refine  or  alloy,  prepare  or  roll  his  plate  material,  or  to 
combine  and  make  his  solders,  alloys,  etc.,  since  the  manufacturers  and 
supply  houses  now  furnish  them  in  all  grades  desired;  yet  a  practical 
knowledge  of  the  methods  and  detail  of  manipulating  them  serves  to 
cultivate  and  make  possible  their  more  skilful  application. 

Of  the  fifty-two  metallic  elements  known  to,  and  so  classified  in 
chemistry,  but  a  few  of  them  in  their  metallic  form  are  used  in  the  me- 


II 


chanics  and  arts  pertaining  to  dentistry;  hence,  in  this  connection  it  is 
only  necessary  to  refer  to  or  consider  those  the  physical  properties 
and  characteristics  of  which  are  of  common  use  and  application  for 
practical  purposes,  and  which  are  contained  in  the  following  table: 


Name. 

1.  Gold. 

2.  Platinum. 

3.  Iridium. 

4.  Copper. 

5.  Silver. 

6.  Zinc. 

7.  Lead. 

8.  Tin. 

9.  Bismuth. 

10.  Cadmium. 

11.  Antimony. 

12.  Aluminum. 

13.  Iron. 

14.  Nickel. 


Metallurgy  divides  the  metals  into  two  groups 
noble  and  Base        known    as    the    noble    and    the    base,    so    classified 
metals.  because  of  their  affinity  for  and  property  of  com- 

bining with  oxygen. 
The  former,  having  less  affinity,  do  not  so  readily  combine  with  it 
by  absorption  from  the  atmosphere,  and  are  more  easily  separated  from 
its  combination  when  subjected  to  heat;  while  the  latter,  having  a  greater 
affinity,  and  absorbing  it  more  readily,  are  separated  with  much  more 
difficulty  because  their  compounds  are  not  decomposed  by  heat  alone. 

Noble  Metals.  Base  Metals. 

Gold.  Copper.  Cadmium. 

Silver.  Tin.  Antimony. 

Platinum.  Zinc.  Aluminum. 

Iridium.  Lead.  Iron. 

Bismuth.  Nickel. 


•mbol. 

Fusing 

Poin^ 

Fah. 

Cent. 

Au. 

2016 

1 102 

Pt. 

3632 

2000 

L. 

More  refract 

ory  than  Pt 

Cu. 

1996 

1091 

Ag. 

1873 

1023 

Zn. 

773 

412 

Pb. 

617 

326 

Sn. 

442 

228 

Bi. 

507 

264 

Cd. 

442 

228 

Sb. 

842 

450 

Al. 

1292 

700 

Fe. 

3000 

1600 

Ni. 

3000 

1600 

€U$$ific<itioii. 

12 

CDcmicdl  ana  PDvsical  Properties. 

While  all  metals  possess  distinct  individual  properties  characteristic 
'  of  themselves,  it  becomes  necessary  for  us  to  consider  only  those  of  such 
practical  importance  as  render  them  useful  and  applicable  to  our  pur- 
poses. 

While  all  metals  are  more  or  less  susceptible 
Cbemical  BCtiOn.      to  the  action  of  the  secretions  of  the  mouth,  gold 
and  platinum  are  the  least   so,  and  of   these  two 
platinum  always  withstands  this   influence  and  retains  its  color  much 
better  than  gold,  which  is  due  mainly  to  the  fact  that  platinum  is  com- 
monly used  in  the  pure  state,  and  gold  in  the  alloyed  state. 

Each    metal   possesses    a    characteristic   color, 
Color.  varying  from  the  grayish-white  of  silver  and  plat- 

inum to  the  muddy  blue  of  lead;  and  from  the  rich 
bright  yellow  gold  to  the  dark  red  of  copper;  each  of  which  is  always 
modified  more  or  less  by  alloying. 

Gold  and  platinum,  however,  possess  a  metallic  luster  and  colors 
which  are  in  contrast  more  pleasing  to  the  eye,  and  more  in  harmony 
with  surroundings,  and  which  are  the  least  susceptible  to  change  by  the 
chemical  action  of  the  secretions. 

Odor  and  taste  are  possessed  by  most  metals 
Odor  attd  taste*  to  such  an  infinitesimal  extent  that  it  is  almost  un- 
necessary to  mention  them.  Copper  and  zinc, 
however,  have  the  most  definite  metallic  odor  and  taste,  but  as  this  is 
apparent  only  when  they  are  subjected  to  a  temperature  higher  than 
that  of  the  body,  and  they  are  used  only  for  the  purpose  of  alloying,  the 
characteristic  is  of  no  especial  importance. 

All  metals  are  capable  of  being  reduced  to  a 
TU$ibiHty*  liquid   state   under   the   influence   of  heat,   but  the 

melting  point  or  degree  of  fusibility  differs  greatly, 
and,  like  the  color,  is  modified  by  alloying.  The  practical  infusibility 
of  platinum  of  any  thickness  greatly  facilitates  some  classes  of  work, 
and  the  controlling  at  will  of  the  fusing  point  of  gold  by  alloying  makes 
the  assemblage  of  innumerable  parts  and  the  art  of  soldering  a  com- 
paratively easy  and  simple  matter. 

Malleability  is  the  inherent  property  of  a  metal 
malleability.  which  admits  of  its  being  hammered  or  rolled  into 

thin  sheets  without  destroying  the  continuity  of  its 
surface,  and  permits  of  its  easy  manipulation  and  adaptation. 

Ductility  is  the  property  which  admits  of  being 
Ductility*  drawn  out  into...lengths  of  a  small  diameter,  such  as 

wire. 


13 

Tenacity  is  the  property  of  molecular  resistance 

tenacity.  I-*^  tension,  upon  which  depends  the  strength  of  the 

metal. 

In  studying  the  accompanying  table,  it  will  be  noted  that  gold, 

while  ranking  first  of  tlie  five  principal  metals  most  commonly  used, 

in  malleability  and  ductility,  ranks  last  in  tenacity,  but  this,  of  course, 

refers  to  pure  gold,  the  tensile  strength  of  which  is  greatly  increased 

by  alloying  with  copper,  silver  or  platinum. 

Malleability.  Ductility.  Tenacity. 

Rank  I.       Gold.  Gold.  Iron. 

"      II.     Silver.  Silver.  Copper. 

"      III.  Copper.  Platinum.  Platinum. 

"      IV.    Platinum.  Iron.  Silver. 

"      V.      Iron.  Copper.  Gold. 

E^»)VS!CciS  Processes. 

The  physical  processes  which  mostly  concern  the  dentist  in  the 
manipulation  of  the  metals  to  accomplish  the  necessary  and  desired 
physical  changes  are  those  of  soldering,  welding,  annealing,  tempering, 
and  alloying,  and  a  clear  conception  of  each  is  of  infinite  importance 
in  their  use. 

Soldering  is  the  process  of  uniting  surfaces  of 
metal  by  fusion  or  superficial  alloying. 

Welding  is  the  process  of  uniting  surfaces  of 
melding.  metal  by  molecular  attraction  under  heat  and  pres- 

sure. 

Annealing  is  the  process  of  softening  or  secur- 

Unncaling.  ing  increased  malleability,  and  as  all  metals  expand 

under  the  influence  of  heat,  they  in  turn  become 

softened  because  of  the  separation  of  the  molecules  produced  by  this 

expansion. 

To  accomplish  this,  they  should  be  slowly  heated  to  a  cherry-red 
and  allowed  to  cool  gradually,  though  plunging  gold  into  water  or 
alcohol  does  not  interfere  with,  and  the  latter  seems  to  even  increase, 
its  softness,  while  aluminum,  fusing  at  a  cherry-red  heat,  is  best  annealed 
by  coating  each  surface  with  oil,  then  igniting  same  and  allowing  it  to 
burn  off. 

Tempering  is   the   process   of  hardening.        In 
tempering.  gold,  platinum,  silver,  copper,  etc.,  it  obtains  as  the 

result  of  manipulation  and  consecutive  working,  due 
to  a  molecular  condensation ;  while  in  iron  containing  carbon  (steel)  sud- 
den thermal  changes  from  various  degrees  of  heat  produce  hardness  in 


14 

proportion  to  the  quantity  of  carbon  present,  and  the  manner  and 
method  of  cooUng;  while  in  some  alloys  the  reverse  condition  obtains. 
The  accompanying  table  is  indicative  of  the  heat  and  color  neces- 
sary in  tempering  the  various  kinds  of  instruments  used.  (Essig:  Am 
Textbook,  Pros.  Dent.,  pp.  131.) 


Temperature. 

Color. 

Use. 

430  to  450 

Fah. 

Light  yellow. 

Enamel  chisels. 

470  Fah. 

Med. 

Excavators. 

490  Fah. 

Brown      " 

Pluggers. 

510  Fah. 

purple. 

Saws,  etc. 

520  Fah. 

Purple. 

Wood-cutting  tools. 

530  to  570 

Fah. 

Blue. 

Clamps,    etc.,   when    elas- 
ticity  is   desired. 

As  alloys  are  a  combination  of  two  or  more 
mioying.  metals,  alloying  is,  of  course,  the  process  of  com- 

bining metals,  and  is  of  material  significance  be- 
cause so  few  are  now  used  in  their  pure  state.  Most  metals  enter  freely 
into  combination  with  others,  the  alloy  resulting  frequently  possessing 
characteristics  entirely  different  from  those  of  any  one  of  the  component 
parts. 

They  always  fuse  lower  than  the  highest  fusing,  and  often  lower 
than  the  most  easily  fusible,  and  in  compounding  them  the  least  fusible 
should  usually  be  melted  first  in  a  clean  crucible,  and  the  others  added 
in  relation  to  and  in  accordance  with  their  fusibility,  after  first  carefully 
weighing  out  the  proper  proportions. 

Alloys  of  gold,  copper  and  silver  can  be  melted  and  incorporated 
almost  simultaneously  with  comparative  ease,  while  those  containing 
platinum  or  zinc  are  more  difhcult.  The  former  is  usually  added  by 
feeding  it  into  the  molten  mass  in  thin,  ribbon  or  foil  form,  while  the 
latter  is  best  incorporated  in  the  shape  of  brass  or  some  other  alloy  of 
known  formula,  because  of  the  rapid  volatilization  of  the  rnetal.  When 
zinc  is  to  be  added  in  the  pure  state,  the  proper  quantity  should  be 
weighed,  broken  into  small  pieces  and  each  piece  coated  with  a  film  of 
paraffin  or  wax,  then  quickly  carried  into  the  molten  mass  with  pliers. 

In  this  work  it  is  necessary  that  one  should  be  familiar  with  the 
table  of  weight  used  for  the  purpose. 

Troy  Weight. 

24  grains  (gr.)  =  i  pennyweight  (dwt.). 

20  pennyweights  (dwt.)     =  i   ounce  (oz.). 
12  ounces  (oz.)  =1  pound  (lb.). 


15 

Scale, 
lb.     oz.      clwt.       gr. 
I  ==  12  =  240  ^^  5760 

I  =      20  :=      480 
I   =  24 

Consideration  of  tbc  metals. 

The    color,    malleability,    compatibility,    slight 
Gold.  susceptibility  to   the    chemical    influences    of    the 

secretions,  and  other  qualities  possessed  by  gold 
make  it  easily  the  nearest  approach  to  the  ideal  for  universal  use,  and 
while  the  higher  artistic  and  esthetic  tendency  should  always  be  to 
avoid  its  conspicuous  display  in  the  mouth  as  much  as  possible,  its 
sphere  of  usefulness  is  unlimited. 

Owing  to  its  extreme  softness  in  the  pure  or  unalloyed  state,  how- 
ever, it  must  be  combined  with  other  metals  which  will  impart,  to  a 
desired  degree,  the  stiffness  and  strength  necessary  to  withstand  the 
stress  and  wear  imposed,  without  appreciably  afifecting  its  other  quali- 
ties, and  the  ease  with  which  it  may  be  thus  alloyed  greatly  enhances 
its  value. 

In  prosthetics  the  use  of  gold  in  the  pure  form  is  necessarily  lim- 
ited, being  usually  confined  to  work  where  a  perfect  adaptation  is  in- 
dicated, such  as  backings  for  porcelain  facings,  individual  bands,  etc., 
where  it  is  to  be  afterward  reinforced,  and  also  as  a  solder  for  platinum 
work. 

In  alloying  gold  the  term  karat  is  applied  to 
Hafat.  the  degree  of  fineness,  and  designates  the  propor- 

tion of  pure  gold  to  the  ratio  of  24  parts.  Thus 
24  K.  is  virgin  pure,  while  18  K.  is  composed  of  18  parts  of  gold  and  6 
of  alloy. 

Platinum     is     rapidly     accjuiring    aii     extensive 
Platinum.  sphere  of  usefulness  in  dental  art,  and  because  of 

its  many  admirable  physical  properties  is  second 
only  to  gold.  Those  of  malleability  and  practical  infusibility  render  its 
manipulation  more  or  less  easy,  and  have  made  possible  the  success  of 
porcelain  work  in  the  various  phases  of  its  present  application;  and  it 
withstands  the  chemical  action  of  the  secretions  so  much  better  than 
gold  as  to  rank  first  in  compatibility  with  the  tissues,  which  take  most 
kindly  to  it.  It  is  also  used  extensively  in  alloying  gold  to  which  it  im- 
parts special  properties. 


The    use    of    iridium,    the    physical    properties 

Tridiunt.  of  which  resemble,  but  are   more  refractory  than 

platinum,   is   confined   to   alloying  with  the   latter, 

the  combination  forming  a  tougher,  harder  metal,  such  as  is  indicated 

in  post  material  for  dowel  crowns  and  other  instances  requiring  more 

than  ordinary  strength. 


For  the  purpose  of  reducing  the  fineness  and 
JTIIoys  Of  Gold.  increasing  the  strength  of  gold,  copper  and  silver 
are  mainly  used  as  the  alloy,  usually  in  the  propor- 
tion of  two  parts  of  copper  to  one  of  silver.  The  former  imparts  hardness 
and  elasticity,  and  the  latter  pliability  and  strength,  together  with  a 
preservation  of  the  original  color  which  copper  alone  would  change, 
except  where  the  desired  fineness  of  the  gold  after  alloying  would  not 
admit  of  sufficient  proportions  of  same  to  possess  the  requisite 
strength,  when  platinum  is  added  in  small  proportions  to  secure  this 
result. 

For  crown  and  bridge  work,  where  strength  and  good  color  should 
be  combined  and  are  prerequisites,  the  gold  most  generally  used  to  the 
best  advantage  is  of  about  22  K.  fineness,  which  is  necessary  to  resist 
or  secure  immunity  from  the  chemical  action  of  the  secretions,  retain 
its  color  and  luster  and  withstand  the  stress;  and  is  used  in  plate  vary- 
ing from  28  to  30  U.  S.  Standard  Gauge. 

The  following  are  three  common  formulae  used  for  this  purpose: 

21.6  K.         No.  3.  21.6  K. 

90  parts.  Coin  gold,  50  parts. 

5      "       Pure      "  45      " 

5      "  "      silver,  5      " 


No.  I.         22  K. 

No.  2. 

Pure  gold,       22  dwt. 

Pure  gold. 

"      copper,     I 

"      copper. 

silver,      18  gr. 

"      silver, 

Platinum,             6  gr. 

The  United 

Coin  Gold.          10, 

was   for  man 

plate  which  was  used  exclusively,  but  which  is  not 
employed  so  extensively  now  because  of  the  extreme  hardness  of  gold 
alloyed  with  copper  alone,  and  of  the  objectionable  reddish  color,  which 
is  not  so  pleasing  to  the  eye,  especially  when  contrasted  by  proximity 
with  the  bright  yellow  of  a  pure  gold  filling.  It  may  be  used  to  good 
advantage,  however,  in  combination  with  pure  gold  and  silver  in  proper 
proportions,  because  of  the  definite  knowledge  of  the  proportion  of 
copper  contained. 


Gold  and  platinum  alloy  is  indicated  wherever 

Gold  additional  strength  and  springy  elasticity  are  desired, 

and  PIcltinutn.  such  as  clasps,  and  for  stiffening  the  work  over  jjarts 

which  will  be    subjected    to    more    than    ordinary 

stress,  which  property  the  addition  of  platinum,  one  part  in  24,  imparts 

to  the  alloy.    The  following  formula  is  used  for  the  purpose: 


Pure  gold, 

20  parts 

Pure  copper. 

2       " 

Pure  silver, 

I   part. 

Platinum, 

I       " 

Platinized  gold  is  a  form  of  plate  made  by  fusing 
Platinized  Gold.  pure  gold  over  one  surface  of  platinum,  which  upon 
being  passed  through  the  rollers  then  ])resents  a 
smooth,  unbroken  surface  of  each  metal.  It  is  much  used  in  gold 
work  where  infusibility  seems  desirable,  and  the  presentation  of  a  sur- 
face of  gold  preferable  to  that  of  platinum.  It  is  also  frequently  useful 
as  a  backing  for  porcelain  facings  because  of  the  advantage  of  control- 
ling or  preserving  the  color  by  placing  next  to  the  porcelain  whichever 
surface  may  cause  the  least,  or  produce  the  most  desirable,  change. 

Solders. 

The  advent  of  porcelain  work  and  the  use  of 

Platinum  Solder.       high   fusing    "bodies"    has    created   a   demand    for 

a  solder  more  infusible  than  pure  gold,  which  was 

previously  used  for  the  purpose,  in  order  that  joints  so  made  would 

not  be  affected  by  the  high  degree  of  heat  necessary  to  fuse  or  vitrify 

the  body. 

If  there  is  absolute  contact  of  the  parts  to  be  united,  pure  gold  can 
be  successfully  used,  because  if  thoroughly  and  sufficiently  fused,  it  be- 
comes an  integral  part  of  the  platinum  by  alloying  with  it;  but  in  ex- 
tensive work  platinum  solders  are  an  advantage  because  of  overcoming 
the  possibility  of  a  change  in  the  relation  of  the  parts,  caused  by  the 
shrinkage  of  the  porcelain,  which  is  considerable. 

Such  solders  are  now  prepared  for  the  purpose,  ranging  from  10 
to  40  per  cent  of  platinum  in  combination  with  gold,  but  less  than  20 
per  cent  is  of  no  advantage,  and  more  than  25  per  cent  is  unnecessary. 
They  may  be  easily  compounded  by  thoroughly  fusing  the  gold  and  then 
feeding  into  the  molten  mass  the  desired  proportion  of  platinum  in  foil 
or  ribbon  form,  after  which  it  should  be  hammered  out  and  remelted 
several  times  to  insure  a  thorough  admixture. 


i8 

Gold  solders  are  alloys  of  gold  so  compounded 
Gold  Sold^fS*  as  to  fuse  slightly  lower  than  plate  of  the  same  fine- 

ness or  karat;  should  be  composed  of  the  same 
metals  to  preserve  a  close  resemblance  in  color,  and  differ  only  in  the 
incorporation  of  a  metal  which  will  reduce  the  fusing  point  and  impart 
flowing  properties.  Thus  a  20  K.  solder,  for  instance,  should  fuse  read- 
ily on  plate  of  the  same  K.,  otherwise  it  would  not  be  a  solder  in  the 
sense  of  the  meaning. 

Zinc  is  mostly  used  for  the  purpose  of  reducing  the  fusibility  and 
imparting  the  requisite  flowing  properties,  but  should  not  be  in  pro- 
portion more  than  i^  to  2  parts  in  24;  because  if  in  greater  quantity 
the  alloy  would  be  rendered  brittle,  the  strength  thus  diminished,  and 
the  susceptibility  to  chemical  influences  when  exposed  to  the  action  of 
the  secretions  increased.  Solder  01  a  lower  K.  than  is  absolutely  neces- 
sary should  never  be  used,  because  the  lower  the  K.,  the  greater  the 
affinity  for  oxidation  and  the  susceptibility  to  chemical  action;  and  in 
consequence  the  seam  of  union  and  the  surface  exposed  are  always 
rendered  more  or  less  conspicuous;  hence  it  is  desirable  to  begin  with  as 
high  a  karat  as  possible,  so  that  subsequent  solderings  may  be  made 
with  those  of  a  degree  of  fineness  which  will  aid  in  precluding  this  ten- 
denc}^  And  as  the  grades  which  are  prepared  for  our  use  invariably 
run  lower  than  the  karat  stamp  upon  them,  those  of  so-called  16  and 
14  karat  have  but  a  very  limited  sphere  of  usefulness. 

The  following  formulae  give  the  average  composition  of  the  vari- 
ous grades  of  dental  solders: 


22  K.  Solder. 

18  K. 

SoId( 

sr. 

Pure  gold,                 22 

dwt. 

Pure  gold, 

18  dwt. 

Brass,                           2 

(( 

"      silver. 

3      " 

Coin  Solder. 

"      copper, 

I      " 

Coin  gold,                    5 

dwt. 

Brass, 

2      " 

Brass,                            i 

<( 

16  K. 

Sold. 

sr. 

20  K.  Solder. 

Pure  gold, 

II  dwt.. 

12 

gr- 

Pure  gold,                 20 

dwt. 

"      silver, 

3      " 

Dorrance's  alloy,        4 

(( 

"      copper, 
"      zinc. 

I      " 

12 
12 

gr. 
gr. 

14  K.  Solder. 
Pure  gold,  14  dwt. 

"      silver,  5      " 

"      copper,  3      "      12  gr. 

"      zinc,  I     "      12  gr. 


19 

As  most  of  the  scrap  gold  must  or  necessity 
Compoundlnfl  Solders,  be  of  uniform  karat  or  degree  of  fineness  for  the 
reasons  previously  mentioned,  and  because  of  the 
ease  of  securing  the  various  karats  of  plate  and  solder  by  the  dentist, 
it  is  scarcely  necessary  to  observe  or  be  familiar  with  the  method  of 
ascertaining  and  computing  the  fineness  of  gold  to  any  extent,  but  as 
it  may  often  be  desirable  to  compound  solders  it  is  well  to  know  the 
method  of  reducing  scrap  to  the  various  karats  used. 

The  following  simple  rule   will   enable  anyone  to  reduce  a  given 
quality  of  scrap  to  any  desired  fineness  of  solder. 

Multiply  the  weight  of  gold  Dy  the  karat  and 

Rule.  divide  by  the  desired  karat.    The  difference  between 

the  answer  after  dividing,  and  the  original  quantity 

of  gold,  is  the  quantity  of  alloy  necessary  to  be  added. 

c«,«.«i.  Reduce   4    dwt.,    3    gr.,    22  K.  gold  to  18  K. 

example.  ^ , 

solder. 

4  dwt.  +  3  gr.  (original  quantity)  =  gr.  99. 

99  X  22  (origmal  karat)  =  2178. 

2178  -^  18  (desired  karat)  =  121. 

121  —  99  (dif.  bet.  result  and  orig.  quantity)  =  22. 

Ans.:    22  gr.  of  alloy  should  be  added. 
For  this  purpose  the  alloy  should  of  course  contain  copper,  silver 
and  zinc,  and  may  be  secured  in  the  most  convenient  form  in  the  shape 
of  known  formulae,  such  as  brass,  Dorrance's  alloy,  or  silver  solder. 

Brass     is     composed     of    copper    and     zinc     m 
Brass.  proportions   suitable  for  the  purpose  intended,  us- 

ually varying  from  equal  parts  of  each  to  70  of  cop- 
per and  30  of  zinc,  and  owing  to  its  close  resemblance  to  gold  in  physical 
properties  and  characteristics  is  much  used  in  various  lines  of  work. 
When  used  as  an  alloy  for  gold  in  compounding  solders,  its  definite 
formula  should  of  course  be  ascertained,  and  that  composed  of  copper 
50,  zinc  50,  is  the  best  for  the  purpose. 

Dorrance's  alloy,  suggested  by  Dr.  W.  H.  Dor- 
Dorrance'S  fliloy.       ranee,  is  used  extensively  in  reducing  gold  to  solders, 
being   a   combination   of  the  three  principal   metals 
used,  in  good  proportions,  with  copper  in  the  preponderance.     The  fol- 
lowing is  the  formula: 

Copper,  6  parts. 
Silver,      2      " 
Zinc,        4      " 


20 

Silver  solder  is  an  allov  of  copper,  silver  and  zinc, 

SilPCr  Solder.  with  silver  in  the  greatest  proportion,  and  is  much 

used  in  the  making  of  gold  solders,  as  the  alloy,  as 

well  as  being  an  economical  hard  solder  for  various  lines  of  work  where 

brass  and  German  silver  are  used.    A  common  formula  is : 

Silver,      6  parts. 
C;opper,  3      " 
Zinc,         I  part. 

German  silver  is  used  to  some  extent  in  tempo- 
German  $WvtT,        rary  work  of  all  kinds,  such  as  dowels  for  temporary 
crowns   and  bands  for  matrices,   etc.     It  is   com- 
posed of  copper  and  zinc,  with  the  addition  of  nickel,  which  mcreases 
the  fusing  point  and  gives  a  harder,  tougher  alloy. 
The  following  formula  is  much  used: 

Copper,  50  parts. 
Zinc,        30      " 
Nickel,    20      " 

Fusible  alloys  are  those  in  which  the  lower  fusing 
fusible  Jinoys.  metals  are  combined,  such  as  lead,  tin,  bismuth, 
antimony,  and  cadmium,  and  arc  intended  for  use 
m  making  dies  and  counterdies  for  swaging  in  crown-work,  and  for  the 
purpose  ot  obtaining  models  direct  from  plaster  impressions,  or  from 
the  mouldine  compounds  suggested  by  Dr.  George  W.  Mellotte,  and 
composed  of  potter's  clay  and  glycerine.  The  extreme  fusibility  of 
these  alloys  depends  to  a  great  extent  upon  the  proportion  of  bismuth 
incorporated,  and  varies  accordinglv.  The  following  are  formulae  of 
the  various  known  alloys  of  this  nature: 

Wood's  Alloy.  Newton's  Alloy. 

Bismuth,  8 

Lead,  5 

Tin,  3 

Fusing  point,  200°  F. 

Hodgen's  Alloy.  • 
Bismuth,  8 

Lead,  5 

,  Tin,  3 

Antimony,  2 

Fusing  point,  224°  F. 


Bismuth, 

5 

Lead, 

4 

Tin, 

2 

Cadmium, 

I 

Fusing  point. 

140° 

F. 

Rose's  Alloy. 
Bismuth,             8 
Lead,                   8 
Tin,                      3 
Fusing  point,  174° 

F. 

21 


Mellotte's  Alloy.  Ordinary  Formula. 

Bismuth,  8  Lead,  i 

Tin,  S  '^^"'  ^ 

Lead,  3  Bismuth,  2 

Fusing  pomt,  200"^  F. 

R.  C.  Brophy's  Alloy.  Grouse's  Alloy. 

Bismuth,  3  Bismuth,  8 

Lead,  2^  Lead,  5 

Tin,  2V2  Tin,  5 

Fusing  point,  240°  F.  Cadmium,  i 

Fusing  point,  190^  F. 

Molyneaux's  Alloy. 
Lead,  3 

Tin,  2 

Cadmium,  2 

Bismuth,  5 

Fusing  point,   140°  F. 

The  lower  fusing  of  these  various  well-known  alloys  may  be  cast 
directly  into  plaster,  gutta  percha  or  modeling  compound  impressions, 
without  waiting  for  them  to  dry  out,  and  Dr.  Grant  Molyneaux  recom- 
mends that  such  impressions  should  be  dipped  in  water  just  before 
pouring  with  his  alloy  to  secure  the  best  results. 

While  there  is  probably  but  a  very  limited  use 

Soft  $Old«r,  for   soft  solder,  it  may   sometimes  be  indicated  in 

temporary  work.  The  ordinary  tinner's  solder  is 
composed  of  equal  parts  of  tin  and  lead,  though  any  of  the  fusible  alloys 
will  answer  the  purpose  equally  as  well. 

It  frequently  occurs  that  the  accumulation  of 

Refining  Gold.         scrap  gold  in  the  laboratory  may  become  so  con- 
taminated with  base  metals,  from  contact  and  from 
the  file,  that  it  could  not  well  be  used  over  again  by  melting  and  rolling 
into  plate,  which  convenience  sometimes  requires,  without  being  first 
subjected  to  some  simple  process  of  refining. 

When  the  scrap  is  composed  mostly  of  a  known  degree  of  fineness, 
this  may  be  quite  easily  accomplished  without  resorting  to  the  chemical 
process,  by  what  is  known  as  the  roasting  method. 

This  consists  of  placing  the  scrap  in  a  clean  crucible  with  plenty 
of  borax,  and  applying  heat  until  a  perfect  fusion  is  reached,  when 
small  pieces  of  potassium  nitrate  (saltpetre)  should  be  consecutively 
added. 


This  oxidizing  agent  furnishes  usually  sufficient  oxygen  to  oxidize 
all  base  metals,  which  oxides  are  absorbed  by  the  borax,  and  if  kept 
up  long  enough  will  result  in  so  materially  refining  the  gold  as  to  per- 
mit of  its  being  annealed,  rolled  to  the  desired  thickness  and  used  over 
again. 

Recovering  ana  Refiniitd  Ulaste  Goll 

While  it  is  very  probable  that  the  average  dentist  will  have  neither 
the  time,  inclination  nor  facilities  for  recovering  the  waste  gold  which 
daily  finds  lodgment  in,  or  becomes  attached  to,  sweepings,  rugs,  carpets, 
disks,  strips,  etc.,  yet  the  method  usually  employed  in  obtaining  and  re- 
fining it  may  be  of  some  general  interest. 

The  sweepmgs  and  such  various  articles  as  may  contain  gold  are 
first  placed  in  a  suitable  vessel,  and  subjected  to  a  degree  of  heat  in  a  blast 
furnace  which  will  reduce  them  to  ashes  and  residue,  after  which  this 
latter  is  then  Unely  pozvdcrcd. 

The  gold,  together  with  its  impurities,  can  now  be  separated  from 
most  of  the  ash,  carbon,  sand,  etc.,  by  a  mechanical  process  of  ivashiiig, 
in  which,  because  of  the  high  specific  gravity  of  the  metallic  masses,  the 
latter  will  seek  the  lowest  point,  allowing  the  residue  to  remain  on 
top. 

The  gold  may  now  be  extracted  from  the  remaining  mixture  of 
heavy  material  by  the  following  method :  Treat  with  nitro-hydrochloric 
acid  (aqua  regia),  heat  gently,  agitate  occasionally,  and  then  allow  the 
mixture  to  stand  for  a  few  hours. 

The  solution  is  now  evaporated  until  all  free  acid  has  been  expelled, 
when  it  is  allowed  to  cool,  and  alcohol  and  potassium  chloride  are  added, 
which  precipitates  any  platinum  that  may  be  present. 

The  gold  may  now  be  precipitated  from  the  filtered  solution  by  add- 
ing ferrous  sulphate,  c.p.,  or  heating  it  with  a  solution  of  oxalic  acid, 
when  the  precipitate,  a  fine  brown  powder,  should  be  washed  with  dis- 
tilled water,  placed  in  a  graphite  crucible  and  thoroughly  fused  with 
potassium  nitrate  (saltpetre),  or  borax,  as  previously  indicated. 

The  molten  metal  may  be  then  poured  from  the  crucible  into  a  pre- 
viously warmed  and  oiled  mould,  when  an  ingot  of  pure  gold  is  obtained, 
which  may  be  alloyed,  if  desired,  and  rolled  out  to  suitable  thickness 
for  use.* 


*The  foregoing  is  intended  only  as  the  essence  of  dental  metallurgy,  tinctured  with  practical 
application  in  its  relation  to  crown  and  bridge  work.  I  have  quoted  freely  from  Mitchell's  Dental 
Chemistry,  Hodgen's  Dental  Metallurgy,  and  the  American  Textbook  of  Prosthetic  Dentistry. 
edited  by  Dr.  C.  J.  Essig,  and  am  indebted  to  Dr.  J.  P.  Buckley,  of  Chicago,  for  suggestions 
and  assistance. 


Soldering. 


CHAPTER  III. 

Essential  Requirements:    Cleanliness;  Acid  Bath.   Flux;   Borax;  Method  of  Usinj 
Parr's    Fluxed   Wax,    Liquid    Soldering    Fluids.      Apposition;     Requirements 
and   Method   of   Obtaining.      Uniform    Heat;    Application   and    Require- 
ments.     Difficulties    Encountered:     "Balling   Up,"    Shrinkage,    Base 
Metals,   Gravity,  Fracturing  Porcelain  Facings,  Soldering  Block 
Teeth.    Manipulation:    Soldering  Without  Investment.    Flame 
Blow-pipes.     Soldering  With   Investment,   Gold   Solder- 
ing, Pure  Gold  Soldering,  Platinum  Soldering,  Oxy- 
Hydrogen   Blow-pipe,   Cooling  After   Soldering, 
To  Prevent  Unsoldering.    Sweating  Process. 
Autogenous  Soldering.     Soft  Soldering. 


In  its  application  to  dentistry  soldering  has  rapidly  assumed  the 
significance  of  an  art  of  much  greater  importance  than  ever  attained 
by  those  presupposed  past  masters — the  gold  and  silversmiths.  This  is 
readily  proven  by  the  ease  with  which  the  process  is  now  executed  in 
the  consecutive  union  of  a  multiplicity  of  parts  and  the  building  or 
restoration  of  contour,  as  compared  with  the  work  along  similar  lines 
confined  to  their  province. 

The  ease  and  dexterity  with  which  such  results  may  now  be  ob- 
tained by  the  more  skilful,  however,  compared  with  the  expressions  of 
•doubt  and  even  dread  manifested  by  others,  followed  by  such  discourag- 
ing failures  as  the  burning  or  fusing  of  the  parts,  or  the  fracturing  of 
porcelain  facings,  leads  to  the  very  natural  conclusion  that  in  sucli 
instances  the  lesson  has  not  been  properly  learned,  and  that  the  subject 
merits  and  demands  more  thoughtful  consideration  and  study,  and  more 
persevering  application  than  is  usually  accorded. 

To  this  end  the  dentist  cannot  too  closely  apply  himself  in  the  effort 
to  become  sufficiently  skilled  as  to  render  the  procedure  one  of  simplicity 
and  ease,  together  with  reducing  to  a  minimum,  or  eliminating,  all  attend- 
ing dangers   of  and  liability  to,   accident,  which  in  this,  the  physical 


24 

process  of  uniting  surfaces  of  metal  by  fusion  or  superficial  alloying, 
will  invariably  follow  a  comprehensive  knowledge  of  the  fundamental 
requirements,  and  a  close  observation  of  all  of  the  essentials  concomitant 
with  success. 


€$$enti(il  K^^uirements. 

These  important  considerations  are  cleanliness,  flux,  apposition, 
and  uniform  heat,  and  unless  clearly  understood  from  a  practical  stand- 
point, the  process  involved,  while  perhaps  sometimes  successfully  ac- 
complished, is  necessarily  followed  in  a  more  or  less  perfunctory  manner, 
in  which  case  the  operator  becomes  simply  an  automaton. 

The  thorough  removal  of  all  oxidation  and  de- 

0kaniin($$.  posits   of  foreign  nature   from  the   surfaces  to  be 

united  is  highly  necessary  in  order  that  the  solder 

may  become  thoroughly  attached  or  incorporated,  so  that  the  element  of 

strength  may  be  insured  in  the  union.    This  may  be  secured  by  scraping 

or  filing  the  surfaces,  or  by  treating  them  with  an  acid  solution. 

For  this  purpose  sulphuric  or  hydrochloric  acid, 
J\i\A  Ball).  diluted  with  an  equal  proportion  of  water,  is  used, 

into  which  the  parts  are  immersed  for  a  few 
moments  to  dissolve  and  remove  all  foreign  substances. 

Sulphuric  acid  is  preferable,  and  for  large  work 
Sand  Ball).  should  be  contained  in  a  porcelain  evaporating  dish 

of  proper  dimensions,  as  heat  materially  increases 
its  cleansing  properties.  The  dish  should  then  be  placed  in  a  shallow 
sheet  iron  bowl  partially  filled  with  sand  and  placed  upon  a  tripod  over 
an  alcohol  or  Bunsen  flame,  by  which  means  the  parts  may  be  boiled,  if 
necessary.  As  the  fumes  thus  given  off  are  more  or  less  injurious  when 
inhaled,  some  provision  must  be  made  for  carrying  them  away,  which 
may  be  quite  easily  accomplished  by  attaching  a  hood  to  a  gas  pipe  and 
permitting  the  latter  to  pass  through  a  hole  in  the  window  at  some  acces- 
sible point  (Fig.  17). 

For  small  work  a  much  more  convenient  method  is  to  freshly  mix 
the  solution  each  time  by  pouring  info  a  small  quantity  of  acid  an  equal 
proportion  of  warm  water,  when  the  chemical  reaction  will  generate  heat 
enough  to  thoroughly  clean  the  parts,  after  which  it  may  be  thrown  out. 
For  metal  work  only,  where  no  porcelain  is  used,  this  solution  may 
be  saved  by  placing  it  in  a  large-mouthed  bottle  and  used  indefinitely 
and  effectively  when  cold  by  first  heating  the  parts  to  be  cleaned  and 
then  plunging  them  into  the  acid. 


25 

After  removing-  the  work  from  the  bath,  it  must  always  be  thor- 
joughly  washed  in  clean  water  to  so  dilute  the  acid  as  to  remove  all  traces- 


Fiq.l7. 


of  it  before  heating  in  the  flame,  because  if  this  is  not  carefully  done,  and 
any  traces  of  acid  should  remain,  the  formation  of  the  salts  of  the  baser 
metals  which  is  facilitated  by  the  heat  will  at  once  preclude  the  possibil- 
ity of  soldering  until  again  treated  with  acid  and  this  precaution  observed. 


Tlux. 

As  the  affinity  for  absorbing  oxygen  from  the  atmosphere,  which- 
nearly  all  metals  possess,  is  increased  by  heat,  the  application  of  it  inci- 
dent to  the  process  of  soldering  causes  the  exposed  surfaces  to  become 
rapidly  oxidized,  in  consequence  of  which  it  is  necessary  to  preclude  the 
possibility  of  such  tendency  and  preserve  the  cleanliness  of  the  parts  in 
order  that  the  solder  may  not  be  prevented  from  readily  fusing  and  be- 
coming alloyed. 

Substances  are  used  for  this  purpose  which,  when  fused  over  such; 
surfaces,  keep  them  clean  and  free  of  oxidization,  and  aid  in  the  fusing  and 
alloying.  It  is  equally  necessary  that  the  solder  as  well  as  the  surfaces  of 
metal  be  thus  treated,  because,  being  a  lower  grade  alloy,  it  is  more  easily 
oxidized.  When  not  so  treated  the  neglect  may  not  infrequently  be  the 
cause  of  much  obstinacy  in  fusing,  demanding  a  greater  degree  of  heat 
than  otherwise  necessary. 


26 

^.  Borax  is  most  generally  used  for  this  purpose 

B0f4X*  ^n<i  meets  the  requirements  in  every  respect,  but 

the  common  practice  of  using  it  in  dry  powdered 
form,  in  far  greater  quantities  than  necessary,  is  to  be  most  vigorously 
condemned,  because  when  first  heated  it  expands  to  such  extent  as  to  not 
infrequently  split  the  investment  and  change  the  relation  of  the  parts; 
may  even  flake  or  deface  the  porcelain  if  it  should  come  in  contact  with  it 
by  fusing  upon  it;  always  displaces  the  solder,  and  usually  results  in  the 
presentation  of  a  pitted  surface. 

To  prevent  this  and  secure  the  best  results,  it  should  be  mixed  with 
clean  water  to  the  consistency  of  a  thin  paste,  and  applied,  before  heating 
the  parts,  with  a  small  camel's  hair  brush,  which  admits  of  its  application 
to  the  particular  surfaces  in  the  proper  and  necessary  quantity. 

Owing  to  the  tendency  to  crystallize,  however,  it  is  difficult  to  pre- 
serve  such  consistency,  but  this  may  be   facilitated  by  preparing   and 


Fiq.l8. 


keeping  it  in  a  glass-covered  dish,  where  it  may  be  also  kept  clean  and 
free  from  dirt,  which  is  eminently  desirable.    (Fig.  i8.) 

This  is  a  hard  wax,  containing  an  admixture  of 
PaiT*$  TlUXCd  max.       borax,  which  is  much  used,  and  is  a  convenient 
form  of  flux,  as  the  wax  burns  out,  leaving  the 
borax  deposited  upon  the  surfaces  in  small  proportions. 

Liquid  soldering  fluid  is  now  being  extensively 

CidUid  used  in  dentistry,  and  has  been  by  jewelers  for  a  num- 

Soldcriltfl  fluid.        ber  of  3'ears,  and  is  the  best,  cleanest,  most  desirable 

and  convenient  flux  for  our  purpose.  It  is  a  saturated 

solution  of  equal  parts  of  borax  and  boric  acid  in  water,  and  can  be  more 

easily  and  readily  applied  with  a  camel's  hair  brush  or  small  piece  of 

wood  in  proper  quantity  to  a  better  advantage  than  any  other. 

In  all  instances,  however,  the  flux  should  be  applied  before  heating 
the  object  to  be  soldered,  in  order  that  it  may  be  placed  in  or  carried  to 
every  portion  and-  surface  of  the  metal  upon  which  the  solder  should 
flow  iri  securing  union.  This  is  not  always  possible  if  applied  to  the 
heated  case,  in  which  instances  powdered  borax  is  preferable. 


2.7 

To  facilitate  the  union  between  the  parts,  the  edges  or  surfaces 
should  always  be  in  absolute  contact,  or  as  nearly  so  as  possible,  so  that 
there  may  be  strength  in  the  joint,  and  no  impediment  offered  to  the 
solder  in  flowing  freely  over  the  surfaces  to  be  united. 

In  case  the  proper  relation  necessary  to  be  sustained  will  not  admit 
of  contact,  it  should  then  be  secured  by  filling  in  between  such  edges  or 
surfaces,  thus  bridging  them  over  with  small  pieces  of  the  metal  of 
which  the  work  is  being  constructed.  This  is  usually  best  accomplished 
with  gold  or  platuium  wire  or  plate,  or  some  of  the  foil  or  crystal  golds, 
the  latter  being  preferable  because  of  their  thickness,  which  should  be 
fitted  or  packed  into  place  before  the  case  is  heated. 

UNiform  1)eat 

The  application  and  proper  manipulation  of  heat  In  securing  the  best 
results  is  an  important  feature,  but  because  of  the  under-valuation  or 
over-estimation  of  the  requirements  is  frequently  the  means  of  much 
discouraging  and  unnecessary  labor,  yet  when  properly  applied  with  the 
former  prerequisites  observed,  the  entire  procedure  is  infinitely  simple. 

In  this  connection  it  must  be  remembered  that,  as  the  process  con- 
stitutes the  alloying  of  the  parts,  the  surfaces  to  be  united  must  be  freely 
exposed,  and  then  brought  to  a  degree  of  heat  exceeding,  or  at  least 
equal  to,  the  fusing  point  of  the  solder  before  union  can  obtain. 

DiffictiUies  ENCOHNterca. 

If  this  degree  of  uniformity  is  not  scrupulously  observed,  and  the 
heat  be  directed  upon  the  solder  before  the  parts  are  equally  and  suf- 
ficiently heated  to  permit  of  alloying,  the  aggravating  annoyance  of  "ball- 
ing up^'  is  invariably  the  result. 

This  tendency  of  the  solder  to  assume  globular 

^'Balling  Up."  form  w^ith  more  or  less  obstinate  persistency  is 
due  only  to  the  difference  between  the  size  of  the 
object  to  be  soldered  and  the  relative  degree  of  heat  required  by  it, 
ag  compared  with  the  small  quantity  of  solder  used  and  its  consequently 
greater  fusibility.  If  much  time  be  thus  consumed  the  baser  alloy  con- 
tained in  the  latter  may  be  burned  out,  the  loss  or  depletion  of  which  will 
increase  the  fusibihty  and  decrease  the  flowing  properties  to  such  extent, 
perhaps,  as  not  infrequently  to  cause  the  melting  of  the  parts. 


28 

As  this  is  obvious,  and  since  the  affinity  of  one  metal  for  combining 
with  another  is  increased  by  heat,  it  is  only  necessary  to  first  raise  the 
temperature  of  the  higher  fusing  parts  equal  or  near  to  the  melting 
point  of  the  most  fusible,  when  very  little  further  heat  well  directed  upon 
both  simultaneously  will  result  in  perfect  union  with  little  or  no  effort, 
and  as  the  solder  will  follow  the  heat  or  flow  in  the  direction  of  the  great- 
est degree  of  temperature,  it  can  be  controlled  accordingly. 

As  the  shrinkage  of  solder  increases  in  proper- 
SbrinRage.  tion  to  the  quantity  of  baser  alloy  incorporated,  and 

manifests  itself  to  such  an  appreciable  extent  in  gold 
work,  it  is  imperative  to  use  the  utmost  precautions  toward  preventing 
the  possible  change  in  the  relation  of  the  parts  which  might  thus  ensue, 
and  which  may  not  infrequently  result  in  jeopardizing  the  fit  and  adap- 
tation. 

To  preclude  this  possibility  it  is  necessary  to  observe  the  require- 
ments of  apposition  and  contact  very  closely,  and  in  more  or  less  exten- 
sive work  it  may  be  further  prevented  by  soldermg  each  piece  separately 
first,  so  that  in  the  final  assemblage  of  the  parts  as  little  solder  may  be 
used  and  carried  to  the  fluid  state  as  is  immediately  required  to  secure 
union  and  strength.  Thus  very  large  cases  should  be  soldered  in  sections. 
and  afterward  united. 

Perhaps  paramount  among  the  difficulties  most: 

Tractnrlnd  of  frequently  experienced  is  the  checking  or  fracturing 

Porcelain  TacingS.      of  porcelain  facings,  but  this,  while  seemingly  and/ 
apparently   unavoidable,   is   in   nearly  all   instances 
due  to  the  most'  flagrant  negligence,  in  so  far  as  soldering  is  concerned. 

In  this  connection  it  is  necessary  to  consider  the  fact  that  a  porce- 
lain facing  constitutes  and  presents  two  distinct  substances,  the  mineral 
and  the  metal — the  porcelain  and  the  pins — each  of  which  possesses  phy- 
sical properties  which  are  affected  very  differently  by  the  heat  to  which 
they  are  subjected. 

The  mineral,  absorbing  heat  very  slowly  and  gradually,  retains  it 
for  a  considerable  length  of  time,  while  the  metal  absorbs  it  readily,  and 
gives  it  off  or  cools  with  equal  rapidity ;  consequently,  in  the  process  of 
soldering,  the  utmost  care  must  be  exercised  in  applying  the  heat  so 
gradually  and  uniformly  from  the  very  outset  that  the  porcelain,  which 
is  a  friable  material,  will  receive  it  either  preceding  or  at  least  simultane- 
ously with  the  platmum  pins,  in  order  that  the  expansion  which  takes 
place  in  each  may  occur  evenly  and  uniformly.  It  is  invariably  this  uneven 
expansion,  wherein  that  of  Ih^^  porcelain  is  not  sufficient  to  accommodate 
that  of  the  pins,  which  causes  the  fractures  occurring  across  the  surface  of 
the  facing,  always  radiating  from  the  pins.     To  various  other  reasons^ 


29 

however,  may  sometimes  be  attributed  this  difficulty,  but  the  percentage 
is  very  small  as  compared  with  that  of  uneven  expansion. 

Such  other  cases  may  be  from  impingement  due  to  the  shrinkage  of 
the  solder  and  augmented  by  too  close  proximity  of  parts  with  each  other 
to  accommodate  this  shrinkage;  from  overhanging  edges  of  backings, 
vv'hich  in  contracting  necessarily  impinge  upon  the  edges  of  the  facings, 
causing  innumerable  small  checks  along  such  edges;  to  perforating  the 
backings  with  openings  much  too  large  for  the  reception  of  the  pins, 
thus  permitting  the  solder  to  run  in  between  backing  and  facing;  or  to 
carelessness  in  bending  the  pins  (to  retain  the  backings),  in  such  manner 
as  to  produce  a  constant  strain  on  the  porcelain  immediately  surrounding 
their  attachment.  As  a  proof  that  it  is  either  uneven  expansion  or 
faulty  adaptation  of  the  backing,  it  is  noticeable  that  facings  seldom  if 
ever  check  in  porcelain  work  where  they  are  subjected  to  even  a  much 
higher  degree  of  heat. 

Where  there  has  been  extensive  resorption  of 
Soldering  tissue  it  will  sometimes  be  desirable  to  use  what  are 

Block  known  as  gum  blocks.   Because  of  the  curve  of  these 

€C(tb.  blocks  there  would  be  more  or  less  liability  of  frac- 

ture, even  in  skilful  hands  were  a  single  backing  to 
be  used  for  the  whole  block.  By  a  very  simple  method,  however,  blocks 
of  three  and  even  four  or  more  teeth  may  be  safely  utilized,  thus  avoiding 
the  unsightliness  an<l  uncleanliness  of  joints  which  would  result  from 
vising  single  gum  teeth.  This  absence  of  joints  is  especially  desirable 
when  restoring  the  anterior  upper  teeth,  and  in  replacing  the  four  in- 
cisors a  most  artistic  result  may  often  be  attained  with  a  single  gum 
block;  In  using  these  blocks  each  tooth  in  the  block  should  be  backed 
separately,  the  backings  being  so  placed  that  they  would  not  absolutely 
touch.  In  adapting  the  blocks  to  the  piece  to  which  they  are  to  be  attached, 
care  should  be  employed  to  so  fit  them  that  the  minimum  of  solder  will  be 
required  to  effect  union.  There  will  be  no  danger  of  cracking  the  block 
during  this  last  procedure,  because  the  base  to  which  attachment  is  made 
sliould  afford  ample  resistance  to  the  slight  shrinkage  of  the  solder  at  the 
bases  of  the  separate  backings. 

Another    not    unusual    occurrence    during   the 

Base  IttrtalS.  process  of  soldering  is  the  appearance  of  small  holes 

or  perforations  on  the  surface  of  the  metal.  These 
are  usually  due  to  the  presence  of  some  of  the  baser  metals,  which  may 
become  attached  by  contact  with  the  dies  in  swaging;  from  a  file  contain- 
ing same,  or  from  the  work  bench,  and  can  only  be  avoided  by  always 
carefully  treating  the  piece  to  an  acid  bath  immediately  preceding  each 
application  of  heat. 


:30 

■:  "  In   extensive   work    it   is   always    desirable  to 

Gf^Vity*  observe  the  laws  of  gravity  as  much  as  possible,  for 

while  it  is  true  that  the  solder  will  follow  the  heat, 
and  its  flowing  may  be  so  controlled  in  a  measure,  when  used  in  con- 
siderable proportion  its  weight  will  naturally  cause  it  to  seek  the  lowest 
point ;  hence  it  frequently  becomes  necessary,  especially  in  large  cases 
for  the  anterior  part  of  the  mouth,  where  the  curvature  is  greater,  to 
change  the  position  of  the  case  as  the  soldering  progresses  in  order  to 
retain  the  mass  in  the  desired  location  when  in  the  fluid  state. 


manipiilation. 

Closely  following  a  consideration  of  the  requirements  and  difficul- 
ties encountered  in  this  work  is  the  importance  of  practical  manipulation 
in  its  various  phases,  the  proper  execution  of  which  renders  the  proce- 
dure easy  and  simple. 

In  soldering  bands,  caps,  and  cusps,  where  no 

Soldering  investnient  is  necessary  to  sustain  the  relation  of  the 

mitbOUt  Tnvcsttntnt*    parts,  the  work  is  more  easily  accomplished  because 

of  the  greater  opportunities  for  securing  uniformity 

of  heat,  and  can  usually  be  done  in  the  flame  of  an  alcohol  lamp  or  Bunsen 

burner  with  ease;  but  the  manner  of  holding  the  object  in  the  flame,  and 

the  material  of  which  the  instruments  for  the  purpose  are  made  bear 

materially  upon  the  dexterity  and  simplicity  with  which  the  procedure 

may  be  accomplished. 

"^  As  dififerent  parts  of  the  flame  vary  in  the  degree 

TIatne.  of  intensity  of  heat,  it  is  of  importance  that  the  object 

be  held  in  a  proper  relation  to  the  same  in  order  that 
the  soldering  may  be  more  easily  accomplished.  The  flame  consists  of 
an  outer  sheath  varying  in  color  from  a  dark  blue  at  the  base  to  a  yellow* 
ish  white  at  the  point,  which  envelops  a  central  cone  of  light  bluish  eolor> 
at  the  summit  of  which  the  greatest  degree  of  heat  is  present  (Fig.  19). 

Fine-pointed  pliers  should  invariably  be  used  and  the  object  should 
be  held  at  a  point  as  remote  from  the  surface  to  be  soldered  as  possible, 
so  that  the  pliers  will  not  absorb  the  heat.  Because  of  this  tendency, 
steel  instruments  should  seldom  be  used,  while  those  made  of  nickel,  or 
its  alloy,  or  of  steel  with  fine  platinum  points  answer  the  purpose  much 
better  because  they  absorb  so  little  heat  that  they  may  be  held  comfort- 
ably in  the  hand. 

In  soldering  platinum  with  pure  gold  the  use  of  flux  is  not  impera- 
tive, for  the  reason  that  both  metals  are  pure  and  devoid  of  alloy,  which 


31 

greatly  diminishes  their  susceptibiUty  to  oxidation,  and  the  ordinary 
mouth  blowpipe  (Fig.  20)  is  all  that  is  necessary;  while  platinum  solder 
up  to  twenty-five  per  cent,  can  be  successfully  used  with  the  "combina- 
tion^' blowpipe  and  bellows   (or  compressed  air)   (Fig.  21),  or  may  be 


equally  well  done  with  the  gasoline  blowpipe,  a  successful  and  convenient 
style  of  which  includes  a  burner  and  is  manufactured  by  Dr.  R.  C.  Brophy^ 
of  Chicago,  111.  (Fig.  22),  or  small  pieces  of  platinum  work  where  the 
contact  and  relation  can  be  sustained  by  proper  adjustment,  and  where 


riq.20, 

no   investment  is  .necessary,   can  very  often  be  soldered   in  the   electric 
furnace  with  much  convenience. 

Where    the    case    is    necessarily    invested    the 
Soldering  process  is  usually  considered  as  a  somewhat  more 

Ulitb  Investment..      difficult    and    arduous    task,    which    for   very  ,  good 
reasons  it  unfortunately  often  proves  to  be,  the  prin- 
cipal one  of  which  is  a  failure  to  properly  and  adequately  heat  the  entire 
case  before  attempting  to  solder. 


It  should  first  always  be  placed  upon  a  Bunsen  or  gasoline  burner 
and  allowed  to  remain  sufficiently  long  to  become  gradually  and  thor- 
oughly heated,  which  may  be  hastened,  if  necessary,  by  applying  and  di- 


Ficj.22. 


recting  the  heat  with  the  "brush"  flame  from  the  blowpipe,  to  the  under 
;surface  in  conjunction  with  the  burner.  Then,  when  it  shall  have  reached 
a  temperature  indicated  by  a  red  heat,  the  solder  should  be  consecutively 


33 

applied  in  fairly  good  sized  pieces,  which,  with  the  burner  from  beneath 
to  preserve  a  uniform  heat,  and  a  "pointed"  flame  from  the  blowpipe 
directed  upon  the  parts,  will  easily  and  quickly  accomplish  the  object 
sought  without  useless  expenditure  of  effort  or  energy. 

The  fusing  and  flowing  of  the  solder  in  the  desired  location  and 
direction  may  occasionally  be  facilitated  by  the  use  of  a  fine  pointed  steel 
instrument  when  in^the  partially  fused  op  plastic  state,  after  which  only 
heat  sufficient  to  solidify  the  mass  until  a  smooth  surface  obtains  should 
be  applied. 

In  fusing  gold  solder  of  any  grade  the  require- 
GoW  Soldering.  ments  in  the  degree  of  heat  so  far  as  the  blow- 
pipe itself  is  concerned  are  generally  greatly  over- 
estimated. If  the  case  is  first  properly  heated,  the  combination 
blowpipe  controlled  by  the  mouth  easily  furnishes  all  that  is  necessary. 
and  is  preferable  and  safer,  as  the  danger  attending  the  burning  of  the 
parts  is  always  increased  by  the  use  of  the  bellows,  because  the  control 
is  not  so  perfect. 

To  blow  a  continuous  flame  with  the  mouth  blowpipe  is  a  valuable 
accomplishment  and  can  be  acquired  with  practice  by  nearly  any  one. 

In  platinum  work,  where  the  danger  of  burning 
Pure  is    eliminated,    and    the    requirements    of   heat    are 

Gold  Soldering.  increased  by  the  use  of  pure  gold  as  solder,  the  bel- 
lows will,  of  course,  be  found  convenient  and  useful, 
though  even  then  the  skilful  manipulation  of  the  mouth  blowpipe  will 
accomplish  the  work.  However  it  may  be  obtained,  heat  enough  to 
thoroughly  fuse  the  gold  until  it  becomes  alloyed  zcith  the  platinum,  so 
as  to  occupy  no  apparent  space  except  that  in  the  immediate  joint,  is 
.absolutely  essential  to  successful  results  in  this  work. 

In  small  cases  where  a  laige  investment  is  not 

Platinum  indicated,   platinum,   solders   up   to  twenty-five   per 

Soldering.  cent,  may  be  fused  with  the  bellows  or  compressed 

air,  but  the  necessary  degree  of  heat  to  thoroughly 

and  easily  fuse  them  can,  of  course,  be  best  obtained  from  the  oxy-hydro- 

gen  flame,  which  is  indicated  always  in  extensive  work. 

The  use  of  an  oxy-hydrogen  blowpipe  is  regarded 
Oxy-1)ydrogcn         by  many  as  being  somewhat  complex  and  expensive. 
Blowpipe.  but  is  in  reality  most  simple  and  comparatively  inex- 

pensive. In  manipulating  one  the  illuminating  gas 
should  be  turned  on  first  and  ignited,  and  then  the  nitrous  oxide  valve 
opened  very  slowly  and  gradually,  until  perfect  combustion  is  obtained. 
The  case  should  be  first  thoroughly  heated  with  the  brush  part  of  the 
flame,  after  which  it  is  necessary  to  bring  the  point  of  the  central  cone  in 


34 

contact  with  the  surfaces  to  be  united,  as  this  is  the  heat-producing  por- 
tion.   The  soldering  may  then  be  accomplished  with  ease. 

The  extreme  heat  and  incandescence,  however,  is  very  trying  to  the 
eyes,  and  a  pair  of  smoked  glasses  will  be  found  most  conducive  to 
success  and  comfort.  Fig.  23  illustrates  a  simple  and  inexpensive  ap- 
paratus for  this  work,  manufactured  by  L.  J.  Mason  &  Co.,  of  Chicago, 
Illinois. 

When  the   soldering  has  been  completed,   the 
pooling  After  case  should  remain  over  the  flame  for  a  few  mo- 

SOldcring.  ments  to  prevent  too  rapid  cooling  and  the  conse- 

quent sudden  contraction  or  shrinkage,  after  which 
the  flame  may  be  turned  off  and  the  case  allowed  to  stand  until  cool  enough 


nq.23.  : 

to  handle,  when  it  may  be  then  removed  from  the  investment,  cleaned  in 
acid,  and  finished. 

In  cases  where  an  investment  is  not  indicated 

Co  Present  it  is  frequently  desirable  "to  observe  some  precau- 

(Insoldcring.  tions  to  avoid  the  unsoldering  or  re-fusing  of  parts 

previously  united,  which  is  usually  accomplished  by 

the  mere  presence  of  the  investment  itself  when  such  is  used.    This  may 

always  be  very  easily  prevented  by  coating  or  treating  such  surfaces  with 

crocus   (ferric  hydrate),  or  a  liquid  solution  of  whiting,  or  plumbago,  in 

water  or  alcohol.  . 

The  not  infrequent  occurrence  or  presence  of 

Sweating  small  perforations  in  the  surface  of  the  work  makes 

Process,  it  often  necessary  to  resort  to  some  me?ins  of  filling 

themi  in.     This  is  best  accomplished  usually  by  what 

is  known,  as  the  sweating  process,  which  simply  implies  bridging  them 

over. with  sojder. 

This  may  apply  to  cases  requiring  investment  or  not,  and  the  pro- 


35 

cedure  in  either  instance  indicated  is  to  first  thoroughly  clean  the  parts 
and  then  fit  or  burnish  into  the  openin.g  a  piece  of  pure  gold  plate  or  foil 
of  suitable  dimensions,  which  may  be  held  in  place  by  holding  the  work 
in  a  favorable  position  to  sustain  it,  or  attaching  it  by  the  fusion  of  the 
flux.  A  piece  of  solder  somewhat  larger  than  the  perforation  should  then 
be  placed  in  position,  covering  same,  and  likewise  held  in  place,  and  then 
heat  uniformly  applied  until  the  solder  becomes  firmly  attached  without 
complete  fusion.  In  small  perforations  solder  alone  will  acconiplish  this 
end,  without  the  use  of  a  support  of  pure  gold  or  other  metal. 

Autogenous  soldering  is  the  process  of  uniting 
JIUtoaenous  Soldering,  surfaces  by  immediate  inter-fusion,  without  the  use 

of  a  lower  grade  alloy,  and  while  it  has  no  decided 
advantages,  excepting  that  a  joint  so  made  is  not  increased  in  stiffness  or 
thickness,  and  the  appearance  of  a  seam  of  solder  is  avoided,  it  is  quite 
easily  accomplished  in  uniting  bands  and  attaching  solid  cusps  to  them,  in 
the  execution  of  which  the  surfaces  must  be  perfectly  approximated,  re- 
tained closely  in  contact,  properly  fluxed,  and  held  in  t^ie  flame  until  union 
is  accomplished  by  superficial  fusion.  By  a  little  practice  one  may  become 
quite  skilful,  and  joints  so  made  usually  possess  every  element  of 
strength. 

While  soft  soldering  is  not  to  be  generally  com- 
Soft  Soldering.         mended,    it    is    sometimes    indicated    in   emergency 

cases,  where  some  strength  in  the  union  of  the  parts 
is  required,  as  in  temporary  crowns,  etc.  For  such  purposes  a  solder 
composed  of  equal  parts  of  tin  and  lead,  or  any  of  the  fusible  alloys,  may 
be  used,  either  with  a  soldering  iron  or  bv  placing  them  upon  an  asbestos 
pad  and  directing  the  flame  of  the  burner  upon  them  until  the  solder 
fuses.  A  convenient  flux  for  this  Avork  is  made  by  gradually  adding 
pure  zinc  to  hydrochloric  acid  until  the  chemical  action  subsides  or  the 
acid  refuses  to  take  up  more,  thus  making  a  solution  of  zinc  chloride, 
when  it  may  be  filtered  and  is  ready  for  use.  .■  '  "'i 


Investing  ana  Investment  nidterials. 


CHAPTER  IV. 

Object  of  Investing.     Requirements  of  Material.     Materials    Used.      Physical    Prop- 
erties.       Models.        Requirements  of  an  Investment.        Preparing  Case    for 
Investment.     Hard  Wax.     Adhesive  Wax.      Investing.     Small  Cases. 
Extensive    Cases.     Precautions.     Removing   Wax.      Prepa- 
ration of  Investment.     Drying  and  Heating,     Pre- 
pared Compounds. 


One  of  the  most  important  features  to  be  observed  in  connection 
with  the  process  of  soldering  is  the  proper  investment  of  the  case,  the 
object  of  which  is  to  sustain  the  relation  of  the  parts  and  preserve  a  uni- 
formity of  temperature  during  and  succeeding  the  application  of  heat. 

By  investing  the  parts  the  uneven  or  too  rapid 

Object  heating  or  cooling  of  porcelain  facings  and  the  con- 

Of  Tnvesting.  sequent   attending    dangers    are   obviated,    and   any 

possible  change  in  the  individual  relation  of  the  parts 

while  being  united  or  assembled  is  entirely  overcome. 

A  suitable  compound  for  such  purposes  should 

KcquireincntS  possess  the  essential  properties  of  crystallization,  in- 

OT  materiaU  fusibility,  free  conductivity  and  strength,  and  should 

neither   shrink   nor  expand  appreciably   during   the 

lieating  process. 

Many  substances  may  be  used  in  combination 
materials  Used.       with  plaster  of  paris,  which  is  necessarily  the  basis 
because  of  imparting  the  property  of  crystallization, 
and  which  must  be  incorporated  to  the  extent  of  at  least  50  per  cent. 


57 

The  remaining-  proportion  may  be  then  composed  of  such  materials 
as  will,  by  virtue  of  their  characteristics  and  physical  properties,  meet  such 
requirements.    The  following  are  serviceable : 

Powdered  Silex,  Pulverized  Pipe  Clay, 

Fine  Asbestos,  Powdered  Fire  Brick, 

Beach  Sand,  Magnesium  Sulphate, 

Marble  Dust.  Pumice  Stone. 

A  combination  of  any  of  these  ingredients  in  varying  proportions 
with  the  proper  quantity  of  plaster  will  usually  possess  the  necessary 
qualities,  excepting  pumice  stone,  which,  because  of  its  low  fusibility  and 
inherent  tendency  to  expand,  should  never  be  used,  and  asbestos  in  large 
proportions,  which,  while  serving  to  hold  the  mass  together,  when  mixed, 
is  objectionable  because  of  its  extreme  low  conductivity. 

The  property  of  free  conductivity  is  important 

Physical  Properties,     because  this  materially  lessens  the  time  consumed  in 

heating  the  case,  by  absorbing  and  distributing  the 

heat  more  rapidly  and  evenly,  and  by  thus  retaining  it  the  better  the 

soldering  is  facilitated,   and  the   liability  of   checking  porcelain   facings 

diminished. 

A  tendency  on  the  part  of  any  compound  to  expand  and  crack  open 
vv^hen  subjected  to  the  influence  of  heat  usually  indicates  that  the  texture 
is  too  fine  to  admit  of  the  rapid  evaporation  of  th^  moisture,  and  as 
possible  displacement  of  the'  parts  and  checking  of  facings  is  thereby 
promoted,  the  use  of  such  material  is  objectionable  and  unsafe. 

By  the  addition  of  a  coarser  ingredient  to  the  compound,  however, 
this  fault  may  be  overcome,  and  a  small  quantity  of  fine  shredded  asbestos 
will  also  frequently  eliminate  the  objection  in  a  measure,  without  greatly^ 
reducing  the  property  of  conducting  heat. 

While,  generally  speaking,  all  models  should  h& 
models.  made  of  plaster  alone,   because   of  thus   possessing- 

greater  strength,  smoother  surfaces  and  more  accu- 
rate and  definite  outlines,  while  offering  no  impediment  to  successful 
soldering  when  properly  prepared,  there  may  be  frequent  indications  for 
making  them  of  investment  material. 

In  such  instances  a  material  which  will  shrink  or  expand  appreciably 
is  decidedly  objectionable,  and  the  characteristics  of  that  used  for  sucH 
purposes  must  be  of  known  quantity,  for  the  reason  that  a  degree  of  in- 
accuracy in  the  relation  of  the  parts  and  their  proper  adaptation 
may  result. 

Where  such  a  model  seems  indicated  and  desirable,  and  especially  for 
the  purpose  of  the  final  assemblage  of  the  parts   in  extensive  cases,  a. 


-38 

smooth,  well-defined  surface  may  be  secured  by  first  pouring  a  small 
quantity  of  thin,  well-mixed  plaster  into  the  impression,  then  inverting 
the  cup  until  all  surplus  runs  out,  leaving  only  a  thin  surface  coating, 
when  by  being  immediately  filled  with  the  investment  material,  a  model 
is  obtained  possessing  a  veneer  of  plaster. 

As  the  object  of  investing  is  to  hold  the  parts  in 

Requirements  their   proper    relation   and  afford  protection   to   the 

Of  an  Investment.      facings,  it  is  but  necessary  that  the  investment  should 

be  only  large  enough  to  accomplish  this  end. 

Any  surplus  in  excess  of  merely  meeting  such  a  requirement  increases 


the  heat  necessary  and  adds  to  the  labor  involved  in  the  process  of  solder- 
ing, without  any  possible  advantage. 

In  assembling  the  individual  parts  on  the  model, 
Preparing  Base  for     some  means  should  be  observed  which  will  tempo- 
Tnvestment.  rarily  sustain  their  accurate  relation  until  they  are 

safely  transferred  to  the  investment.  In  this  partic- 
ular it  is  necessary  that  they  should  be  so  securely  united  as  to  prevent 
any  possible  displacement  during  the  process  of  removing  from  the  model, 
and  the  subsequent  imbedding  into  the  investment  material,  with  a  sub- 
stance sufficiently  tough  and  strong  to  withstand  such  procedure. 

This  is  usually  accomplished  by  using  a  hard  or  adhesive  wax  as  a 
medium  of  cementation,  which  in  large  cases  may  be  further  sup- 
plemented by  covering  the  facings  and  crowns  from  the  buccal  or  labial 


39 

surfaces  with  a  thin  layer  of  plaster  or  investment  compound  previous  to 
removing  from  the  articulator.     (Fig.  24.) 

In  interrupted  bridges  or  where  some  adaptation  of  bars  or  rests  to 
a  proper  relation  with  the  natural  teeth  is  indicated,  it  may  often  be  done 
to  better  advantage  after  the  case  is  invested  than  when  on  the  model.  In 
such  instances  by  extending  or  continuing  the  wax  over  these  teeth  so  as 
to  secure  an  impression  of  them  before  detaching  and  investing,  their  ac- 
curate reproduction  may  be  secured  in  the  investment. 

For  the  purpose  of  thus  securely  cementing  the 
Uard  lUax,  parts   a  hard  wax   composed   of  from  two  to   four 

parts  of  resin  and  one  of  wax  is  reliable  and  much 
used.  The  combination  forms  a  stifif,  brittle  substance,  which  for  con- 
venience should  be  rolled  out  into  sticks  of  suitable  size  and  length.  These 
may  be  kept  indefinitely  by  coating  the  surfaces  with  whiting  or  plaster 
to  keep  them  from  adhering  to  each  other.  Parr's  fluxed  wax  may  also 
be  used  for  the  purpose. 

As  the  extreme  brittleness  of  hard  wax  is  some- 
JldbCSiVC    max.         times  objectionable,  a  less  brittle  and  more  adhesive 
compound  may  often  be  found  preferable.     The  fol- 
lowing  formula   gives   an   adhesive   wax  possessing  excellent   qualities : 
White  bee's  wax,  8  oz. ;  pulverized  white  resin,   1^2   oz. ;  gum  dammar, 
i^  oz.     Melt  in  order  named. 

When  the  various  parts  are  securely  and  firmly 
Tltoesting.  united,  the  wax  should  then  be  carried  over  a  con- 

siderable surface  of  the  abutment  crowns  and  caps, 
including  every  portion  of  the  work  not  to  be  subsequently  covered  by 
investment  material.  This  procedure  serves  to  keep  such  surfaces  clean 
and  free  of  dirt,  and  leaves  them  fully  exposed  in  the  investment,  by  guid- 
ing the  flowing  of  same  over  only  those  parts  which  should  be  protected. 

In  all  cases,  ranging  from  a  single  crown  up  to 
$|na11  Cases.  four  or  five  teeth,  the  abutment  crowns  and  caps 
should  be  detached  from  the  model,  previous  tc 
cementing  the  parts,  in  such  manner  as  to  preserve  their  definite  outline 
and  relation.  Upon  being  again  replaced  in  their  proper  position  all  of 
the  individual  parts  may  be  assembled  and  cemented  together,  when  the 
whole  can  then  be  easily  removed  and  invested.  This  eliminates  the  de- 
struction and  investing  of  the  model  and  preserves  it  for  future  use  in 
case  of  desire  or  necessity. 

In  larger  cases,  however,  it  is  not  usually  good 
€xtcn$iV(  Cases,       policy  to  follow  this  procedure,  because  of  the  in- 
creased liability  of  an  inaccurate  replacement  of  the 
abutment  caps  and  crowns,  especially  if  there  be  more  than  two.     In  such 
instances  it  is  always  safest  and  best  after  assembling  and  cementing  the 


40 

parts  firmly  to  first  remove  the  model  from  the  articulator,  and  then  trim 
away  all  surplus  plaster  until  only  enough  remains  to  sustain  the  relation. 
(Fig.  25.)  This,  then,  precludes  the  possibility  of  any  disarrangement 
or  displacement  of  the  parts,  and  the  remaining  plaster  is  of  no  signifi- 
cance if  entirely  submerged  and  completely  covered  with  the  invest- 
ment material. 

The  investmicnt  compound  should  be  mixed  of 

Pf(C3UtiOn$.  a  moderately  thin    and   plastic   consistency,   so  that 

when  the  proper  quantity  is  poured  upon  a  piece  of 

paper  it  will  offer  no  resistance  in  pressing  the  case  down  into  place, 

until  it  is  properly  submerged  and  sufficiently  covered.     If  too  stiff  there 

would  be  danger  of  a  change  in  the  relation  of  the  parts. 

To  make  sure  of  a  close  adaptation  of  the  material  to  the  facings 
and  other  parts,  and  to  hold  them  securely  when  invested,  all  surplus 
wax  and  dirt  should  be  carefully  removed  and  the  case  dipped  in  water 
just  previous  to  bringing  it  in  contact  with  the  investment  material. 


Fic].25. 

The  interior  of  all  crowns  and  caps  unless  previously  well  -filled  with 
plaster  should  then  be  first  thoroughly  packed  with  the  investment  ma- 
terial by  using  a  small  piece  of  wood  or  fine-pointed  spatula;  because  if 
not  perfectly  filled  the  presence  of  air  spaces,  into  which  the  heat  be- 
comes concentrated  during  the  process  of  soldering,  will  materially  in- 
crease the  liability  of  burning  or  fusing  the  parts,  an  accident  which  for 
this  reason  not  infrequently  occurs. 

After   the    investment   has   become   thoroughly 

K^tnovind  Ultax.       hardened  and  the  surplus   trimmed  away,  the  -wax 

should  be  slightly  warmed  by  passing  over  the  flame 

and  removed  as  well  as  possible  with  a  small  knife-blade  or  other  pointed 

instrument,  being  careful  not  to  loosen  or  dislodge  the  parts  in  so  doing. 

Hot  water  may  be  then  poured  upon  it,  but  the  case  should  never 
be  boiled,  for  the  reason  that  such  procedure  disintegrates  the  com- 
pound, interferes  with  its  perfect  crystallization,  and  requires  more  time 
in  drying  out  and  heating  up  than  would  otherwise  be  necessary. 

Choloroform,  being  a  solvent  of  wax,  is  also  used  to  remove  remain- 
ing particles,  but  this  is -entirely  unnecessary,  because  the  wax  will  be  ab- 
sorbed by  the  investment  and  ultimately  burned  out  entirely  during  the 
heating  process. 


41 

As    soon  as  the    wax  has    been  sufficiently    re- 
Prcparation  moved,  the  investment    should    be   trimmed    down 

Of  Tnpesttwent.         until  no    larger    than   is    absolutely    required,   thus 
leaving  all  surfaces  upon  which  the  solder  is  to  be- 
come attached  freely  exposed,  so  as  to  offer  no  impediment  to  the  heat- 
ing of  the  case.     No  danger  will  accrue  from  this  free  exposure  of  the 


Fiq.26. 


parts  if  the  porcelain  facings  are  covered  and  the  interior  of  crowns  and 
caps  well  filled,  and  the  labor  involved  in  the  process  of  soldering  will 
be  materially  lessened. 

The  investment  tor  a  suigle  crown  sliould  be  cut  away  from  the 
approximal  sides  on  a  line  with  the  backing  and  cap.  (Fig.  26. j  Where 
this  is  not  observed  and  the  investment  remains  banked  up  on  these  sides, 


Fia.27, 


the  crown  is  imbedded  into  a  depression,  and  the  soldering  is  made  much 
more  difficult  because  the  flame  and  heat  from  the  blow-pipe  is  thus  de- 
flected from  the  parts. 

This  applies  as  well  to  more  extensive  work,  and  should  always  be 
closely  observed.  The  proper  exposure  of  the  metal  parts  and  the  neces- 
sary trimming  away  of  the  investment  for  larger  cases  is  illustrated  in. 
Fig.  27. 

When  the  preparation  has  been    completed  and 
Drying  and  locating,     all  particles  of  debris  removed,  the  parts  should  then 
be  fluxed,  and  the  case  placed  upon  the  burner  until 
it  grarlually  becomes  sufficiently  heated  to  proceed  with  the  soldering. 


42 

Many  devices  are  provided  for  holding  the  case  in  the  flame,  but  the 
simplest,  most  useful  and  economical  method  is  to  put  it  upon  a  piece 
of  the  ordinary  metal  lathing  used  in  plastering,  which  is  made  of  iron 
and  is  more  or  less  durable,  and  then  place  this  upon  the  spider  over  the 
flame.      (Fig.  28.) 

Several    preparations    possessing     the    required 
Prepared  Compounds,  qualities  to  a  greater  or  less  extent  can  be  easily  pro- 
cured, among    which    may    be   included    Dr.  R.   C. 


Ficj23. 


Brophy's  "Imperial  Investment  Material,"  the  investment  compound 
made  by  the  Consolidated  Dental  Manufacturing  Company ;  "Sump,'' 
prepared  by  the  S.  S.  White  Dental  Manufacturing  Company,  and 
"Teague's  Compound,"  all  of  which  are  of  special  merit  and  can  be 
highly  recommended. 


w  Jj/ 


Requirements  and 
Cecbnique  of  €rown  Construction. 


Indications  and  Requirements. 


CHAPTER  V. 

Indications:    Extensive    Caries.     Accidental   Causes.      Discoloration.      Malformalion . 
Malposition.    Requirements  :   Physiological  Relations.    Anatomical  Relations. 
Stress.    Articulation  and  Occlusion.    Approximal  Contact.     Mechani- 
cal Relations.     Method  of  .Attachment.    Dowels.   Telescoping. 
Fit.     Strength.     Esthetic  Relations. 


Before  one  is  properly  prepared  to  consider  the  manipulative  proce- 
dure incident  to  the  detail  of  construction  of  artificial  crowns,  a  clear 
conception  and  a  thorough  understanding  of  :he  indications  for.  and  re- 
quirements of  such  substitutes  for  the  natural  crowns  of  teeth  as  are 
generally  applicable  today  are  essentially  necessary. 

It  does  not  matter  particularly  in  what  line  of  art  or  mechanics  one 
confines  his  efforts,  to  meet  with  success  in  the  direction  chosen  requires, 
first  of  all,  the  necessit}'  of  formulating  in  the  mind,  or  picturing  in  the 
mental  eye,  the  result  of  the  contemplated  effort  in  the  finished  state, 
before  even  commencing  the  detail  of  its  construction. 

To  thus  conceive  the  possible  result  before  the  execution,  in  a  work 
where  art  and  mechanics  are  so  closely  related  to  nature,  greatly 
enhances  the  possibilities  by  cultivating  the  possession  of  those  lucid  and 
perceptive  ideas  which  are  so  essential  to  success  if  success  is  dependent 
upon  the  attainment  of  special  skill,  as  it  should  be. 

And  yet  while  dentistry  offers  no  greater  opportunities  for  the  ac- 
quirement and  display  of  the  highest  artistic  talent  than  in  the  field  of 
crown-work,  such  prerequisites  alone  will  not  always  insure  success,  but 
must  be  supplemented  by  a  degree  of  accuracy,  facility  and  delicacy  in 
instrumentation  which  will  at  once  inspire  the  confidence  of  the  patient. 

Thus  will  he  be  the  better  qualified  to  obtain  results  more  accurately 
restoring  the  normal  functions  and  more  closely  approaching  a  reproduc- 
tion of  nature ;  and  to  perform  them  for  the  most  nervous,  sensitive 
patients  with  more  gratifying  success  to  all  concerned. 


40 

In  this  field,  as  in  many  others,  those  methods  which  are  quickest 
and  best  are  not  necessarily  synonymous,  and  so  it  often  becomes  a  matter 
of  judgment  and  discrimination  as  to  the  employment  of  the  particular 
method  most  applicable  to  the  case  at  hand,  in  which  the  operator  must  be 
governed  only  by  the  most  scrupulous  and  conscientious  efforts. 

While  there  may  frequently  be  several  methods  of  procedure  that, 
at  the  first  conclusion,  seem  apparently  applicable,  there  is  usually  one  in 
particular  which  upon  closer  observation  will  best  meet  all  of  the 
requirements. 

TnaicatiOHS. 

The  employment  of  artificial  crowns  is  indicated  in  extensive  loss  of 

tooth  structure  from  the  ravages  of  caries,  or  accidental  causes,  and  not 

infrequently  because  of  discoloration,  malformation  and  malposition,  as 

a  means  of  substitution  for  the  correction  and  restoration  of   impaired 

function,  and  relief  from  disfigurement.     There  should  always  be  enough 

tooth  structure  remaining,  however,  to  insure  sufficient  anchorage. 

By  far  tl:c  most  general  indication  is  in  those 

■    -^  ,     .      „    ,  instances  where  the  natural  tooth  structure  has  suf- 

exJcnsiDc  Carles.     ,      ,       .   .  t,,   i       x        .1  r      • 

lerea  such  irreparable  loss  from  the  process  of  caries 

as  to  make  restoration  by  filling,  with  any  assiirance  of  permanency  in 

the  operation,  either  inadvisable  or  impossible. 

In  those  cases,  however,  where  it  seems  a  matter  of  conjecture  as  to 
the  advisability  of  filling  or  crowning,  unless  for  esthetic  reasons,  the 
preference  should  be  given  to  filling,  if  such  procedure  may  seem  to  offer 
an}^  certainty  of  a  reasonable  degree  of  success  and  permanency. 

In  frequent  instances  the  remaining  walls  of  badly  broken  down 
teeth  may  be  protected  and  usefulness  restored  for  many  years  by  the 
insertion  of  a  post  into  the  canal,  and  the  building  of  a  filling  around  it, 
and  such  a  course  is  often  indicated  for  the  reason  that  the  crowning 
operation  may  then  be  deferred  and  become  a  subsequent  and  possibly 
remote  necessity,  which  would  perhaps  add  to  the  aggregate  longevity 
of  the  root. 

Moreover,  the  presence  of  a  well-adapted  filling  is  no  doubt  more 
conducive  to  the  preservation  of  the  normal  condition  of  the  surrounding 
tissues,  than  the  most  skilfully  adapted  crown. 

The  loss  of  a  portion  or  all  of  the  natural  tooth 

JfCCidcntal  Causes,      crown  in  the  anterior  region,  as  the  result  of  a  fall  or 

blow,  or  from  overstrained  masticatory  action  upon 

hard  substances  in  the  posterior  region,  is  by  no  means  uncommon,  and 

usually  calls  for  immediate  relief  in  their  reproduction  and  restoration. 


Discoloration. 


47 

The  presence  of  a  l^adly  discolored  tooth  in  the 
anterior  j^art  of  the  nnjuth,  which  persistently  refuses 
to    succumb   to   repeated    efforts   at  bleaching-,    may 


Fiq.  29. 

often  indicate  an  artificial  substitute  as  the  only  means  of  cfifectually  and 
permanently  remedying  its  C(jnspicuous  and  objectionable  a])pearance. 


In   such   conditions  of  faulty   enamel   formation 

malformation.  as  the  so-called  "'peg'"   laterals    (Fig.   29)     anfl    the 

pitted    enamel   structure,   as   is    frequently   found   to 

exist  in  the  first  permanent  molars  and  the  anterior  teeth   (Fig.  30),  the 


Fiq.  3  I. 


application  of  an  artificial  crown  may  often  be  indicated  as  the  best  means 
of  restoring  usefulness  and  affording  relief  from  disfigurement. 

There  are  frequent  instances  of  simple   irregu- 

inalposition.  larity   of   the   anterior  teeth,   where    the   age   of  the 

patient,  together  with  the  presen*^"  of  caries  or  other 


conditions  may  not  seem  to  warrant  their  correction  by  the  process  of 
regulating.  Often  the  desired  effect  may  be  obtained  by  sacrificing  the 
natural  crowns  and  substituting  artificial  ones  as  the  most  simple  and  artis- 
tic means  of  correcting  the  deformity.     (Fig.  31.) 

Keduiremcnts. 

The  success  of  crown-work  in  the  various  phases  of  its  application, 
and  the  degree  of  permanence  in  the  operation,  combined  with  the  esthetic 
results  obtained,  depends  upon  a  close  observation  of  the  requirements 
from  a  physiological,  anatomical,  mechanical  and  esthetic  standpoint. 

When  it  has  been  determined  that  a  crown  is 
PbysiOlOSical  indicated  or  seems  to  be  the  most  advisable  proce- 

Rcl4tion$.  dure,  it  is  first  necessary  to  ascertain  the  condition  of 

vitality  of  the  immediate  and  surrounding  tissues. 
If  pathological  conditions  exist,  every  effort  should  be  made  to  locate 
and  remove  the  cause,  and  the  usual  remedial  or  medicinal  agencies  should 
be  applied  until  the  tooth  or  root  assumes  as  healthy  and  normal  a  condi- 
tion as  possible  before  proceeding  further  with  the  operation. 

This  particularly  includes  the  thorough  disinfection  of  the  remaining 
tooth  structure,  and  the  removal  of  all  that  may  prove  irritating  to  the 
peridental  membrane.  The  precaution  is  necessary  because  the  presence 
of  an  artificial  crown  should  not  afford  any  more  reason  or  opportunity 
for  the  deleterious  action  of  disease-producing  agencies  than  when  the 
tooth  was  in  a  normal  healthy  condition ;  indeed,  it  should  even  further 
fortify  it  against  attack. 

In  regard  to  anatomical  relations  we  are  gov- 
Jlnatontical  erned  by  the  position  of  the  root  and  the  artificial 

Kclations.  crown  supported  by  it  in  their  relation  to  the  adja- 

cent and  antagonizing  teeth,  which  includes  the  con- 
sideration of  stress,  occlusion  and  approximal  contact. 

The    roots    of   teeth   carrying   crowns   are   sub- 
$trc$$^  jected  to  the  influence  of  stress  in   different   direc- 

tions, according  to  their  location  in  the  arch,  which 
fact  demands  that  the  construction  and  application  of  artificial  crowns 
should  be  made  with  a  view  of  affording  a  degree  of  resistance  sufficient 
to  secure  the  greatest  integrity  of  both. 

As  the  line  of  the  greatest  natural  resistance  is  in  the  vertical  direc- 
tion, every  provision  should  be  made  tending  to  prevent  undue  and  un- 
natural stress,  which  might  ultimately  cause  displacement,  trouble,  or 
possible  loss  of  the  root. 

In  the  anterior  teeth  the  general  tendency  of  the  stress  imposed  is  to 


49 

force  them  outward  and  forward,  which  may  and  sliould  always  be  re- 
lieved as  much  as  possible  by  the  proper  preparation  of  the  root,  the 
restoration  of  approximal  contact,  and  the  method  employed  for  the 
attachment  of  the  crown. 

In  the  bicuspids  the  stress  is  received  in  both  vertical  and  lateral 
directions,  which  demands  a  firm  seating  to  accommodate  the  former  and 
a  strong  method  of  anchorage  to  overcome  the  latter. 

The  molars  are  least  susceptible  to  displacement  for  the  reason  that 
lateral  stress  is  limited  in  proportion  to  the  degree  of  the  normal  accuracy 
of  occlusion  ;  and  as  the  greatest  stress  is  in  the  direct  or  vertical  line, 
the  essential  requirement  is  a  good  firm  seating,  sup[)lemente(l  by  accurate 
■occlusion. 

The    degree  of   usefulness  and   longevity  of  the 

Jlrticulation  and       artificial  substitute  depends  greatly  upon  such  forma- 

OcclUSion.  lion  of  the  articulating  surfaces,  and  in  the  posterior 

region  the  arrangement  of  cusps  and  sulci  in  their 

relation  to  the  antagonizing  teeth,  as  will  restore  their  normal  functions. 

The  arrangement  should  provide  for  correct  position  not  only  when  the 

teeth  are  in  direct  occlusion,  but  also  in  their  articulation  or  the  act  of 

bringing  them  into  occlusion. 

The  evils  of  faulty  and  imperfect  occlusion  are  often  apparent,  and 
result  frecjuently  in  marked  manifestations  of  virulent  peridental  and 
neurotic  troubles. 

The  restoration  of  approximal  contact  is  of  the 
HPtM'OXitnal  Contact,    greatest  importance,  and  is  made  so  because  of  the 
necessity  for  protecting  the  tissues  in  the  interproxi- 
mal spaces  from  the  serious  results  of  irritation. 

These  tissues  promptly  rebel  against  the  slightest  irritating  influences 
to  such  extent  as  to  demand  the  most  stringent  efforts  toward  tb.eir  pro- 
tection and  preservation. 

Due    thought    should    be    bestowed    upon    the 
mechanical  method  of  attachment,  fit  and  strength  of  artificial 

KslatiOi)$.  crowns,  all  of  which  are  so  necessary  and  add   so 

materially  to  the   durability  and  degree   of   perma- 
nency in  the  work  from  a  mechanical  standpoint. 

Two   general   methods   of   attachment    are   em- 
IDctbOd  of  flttachmcnt.  ployed,  each  or  either  of  which  may  be  indicated  by 
the  style  of  crown  required,  and  the  amount  of  tooth 
structure  to  which  the  attachment  may  be  made. 

In  roots  which  are  even  with  or  approximating 

Dowels.  the  gingival  line,  attachment  must  necessarily  be  made 

by  inserting  a  dowel  in  the  direction  of  their  longi- 


50 

tiulinai  axis  to  a  depth,  where  possible,  equal  to  the  leno:th  of  the  crown 
from  cervix  to  incisal  or  occlusal  edge. 

Such  a  mechanical  fixation,  whether  the  dowel  be  previously  attached 
to  crown  or  root,  practically  precludes  the  loosening  of  the  parts  from 
strain,  at  the  line  of  junction,  overcoming,'  leverage  at  that  point  by 
distributing  it  throughout  the  length  of  root,  and  forms  a  most  secure 
means  of  anchorage. 

Where  enough  of  the  root  is  freely  exposed  to 

tCkSCOpittS.  afford  a  firm  grasp  of  the  crown,  the  attachment  may 

be    securely    made    by    telescoping,    in    which    the 

strength  at  the  line  of  junction  naturally  increases  in  proportion  to  the 

surface  of  tooth  structure  covered  by  the  crown. 

Tl:e    relation  existing  between   the   crown    and 
iWdaptaJlOlt— Tit.       root  is  of  the  greatest  possible  importance,  because 
the  ratio  of  subsequent  failure  or  trouble  ari  ing  from 
the  progress  of  caries,  or  from  gingival  or  peridental  irritation,  is  de- 
creased in  proportion  to  the  degree  of  accuracy  in  the  adaptation. 

The  crown  should  be  seated  firmly  upon  the  root,  and  if  no  band  is 
used  the  adaptation  should  be  close  enough  to  make  a  joint  as  flush  and 
impervious  as  possible,  so  that  the  end  of  the  root  may  be  thus  pro- 
tected. 

When  a  band  is  used,  it  should  pass  under  or  within  the  free  margin 
of  the  gum  a  uniform  distance  on  all  surfaces  of  the  tooth  and  only  far 
enough  to  cover  and  protect  the  seam  of  union,  which  should  be  in  such 
close  proximity  to  the  root  as  to  preserve  its  continuity  and  make  a  smooth 
line  of  junctiori  between  the  two. 

The  durability  of  this  work  depends  to  a  very 
Strength.  large  extent  upon  its    inherent    strength,    which    it 

should  always  possess  to  a  degree  sufficient  to  per- 
manently withstand  the  stress  of  mastication,  even  though  it  be  gained 
at  the  sacrifice  of  more  or  less  artistic  results  when  occasion  requires. 
Any  tendency  toward  undue  economy  usually  proves  disastrous. 

These   considerations   embrace   the   field    which 

esthetic  KelatlOlt*.     gives  the  greatest  possible  scope  to  the  individuality 

and  artistic  temperament  of  the  operator,  and  while 

it  is  true  that  art  can  never  entirely  and  completely  take  the  place  of 

nature,  the  aphorism  is  less  applicable  to  this  special  line  of  work,  perhaps, 

than  to  any  other  department  of  dentistry  or  of  art. 

To  secure  the  highest  artistic  results,  the  artificial  crown  should  pre- 
serve the  gingival  outline,  and  the  symmetrical  alignment  of  the  teeth ; 
should  be  proportionate  in  length  with  the  adjacent  teeth,  and  if  of  porce- 
lain should  closely  match  them  in  color,  and  should  correspond  favorably 


in  general  form  and  characteristics  with  its  fellow  member  (^f  the  opposite 
side  of  the  arch. 

As  a  rule,  where  porcelain  is  used  no  metal  should  be  exposed  to 
view  from  any  surface,  unless  purposely  done  to  more  closelv  match  the 
adjacent  teeth  or  the  corresponding  tooth. 

In  instances  where  the  remaining  natural  teeth  are  freely  filled  witli 
gold,  the  artificial  substitute  should  often  carry  fillings  which  will  enable 
it  to  more  closely  resemble  and  harmonize  with  them,  thus  making  detec- 
tion more  improbable,  which  legitimate  deception  is  a  true  evidence  of 
artistic  endeavor. 


Cbe  Preparation  of  Roots. 


CHAPTER    VI. 

rreliminary   Requirements:     Therapeutics.     Feasibility   of   Devitalization:     Physio 
logical   Considerations;   Mechanical   Considerations.     Treatment  of   Hypertrophy, 
Free    Exposure   of  the   Root.     Classification.     Preparation   for    Shell   or   Tele- 
scope Crown:      Requirements;    Restoration    of    Continuity;    Diminution    of 
Coronal   Proportions ;   Paralleling  Converging  or  Diverging  Teeth ;  Opera- 
tive Procedure.     Preparation  for  Shell  or  Telescope  Crown  with  Porce- 
lain   Facing:     Requirements.      Preparation  for  Band  and  Dowel  Crown; 
Requirements;    Operative    Procedure;    Excising   Incisors    and    Cus- 
pids;   Excising  Bicuspids  and  Molars;   Removal  of  Enamel:    Use 
of  Enamel  Cleavers ;  Peripheral  Trimming ;  Shaping  Basal   Sur- 
face.    Preparation  for  Dowel  Crown  without  Band :  Require- 
ments;   Operative    Procedure;    Inseparable   Dowels;    Separ- 
able     Dowels ;       Protection      of      Unsupported       Walls. 
Preparation      of      Canals:      Requirements;       Operative 
Procedure.     Treatment  of   Perforated   Roots.     Treat- 
ment     of      Fractured      Roots :       Posterior      Teeth ; 
Anterior    Teeth,    Prognosis. 


Paramount  among  the  obstacles  in  the  pathway  of  success,  perma- 
nenc}^  and  comfort  in  crown  and  bridge  work  is  the  perfunctory,  unskilfut 
and  profoundly  indifferent  methods  so  often  employed  in  the  procedure 
incident  to  the  treatment  and  preparation  of  roots. 

In  the  entire  subject  there  is  probably  no  one  distinctive  feature  oi 
such  intrinsic  importance  as  the  practical,  scientific  and  skilful  prepara- 
tion of  the  remaining  crowns  and  roots  of  teeth,  for  the  reception  of  arti- 
ficial crowns. 

While  the  proper  and  necessary  operative  procedure  may  be  arduous, 
and  replete  with  attendmg  difficulties,  the  physiological  and  mechanical 
requirements  are  equally  exacting,  and  demand  the  same  degree  of  care, 
precision  and  accurac}'  that  would  be  essential  to  the  preparation  of  the 
foundation  for  any  superstructure  designed  as  a  permanent  evidence  of 
skill  and  usefulness. 

Alore  particularly  is  this  true  in  our  efforts,  because  the  field  of  labor 
is  confined  to  living  sensitive  tissues  which  are  so  responsive  to  unnatiu'al 
conditions  that  any  apparent  negligence  must  sooner  or  later  manifest 
itself,  not  alone  in  evidences  of  failure,  but  also  in  the  serious  discomfit- 
ures accompanying  the  various  stages  of  irritation. 


53 

These  usually  present  in  the  nature  of  gingival  inflammation,  and 
peridental  and  alveolar  absorption,  to  which  conditions  may  be  attributed  a 
very  large  percentage  of  the  troubles  arising,  and  the  absolute  loss  of  many 
teeth.  The  common  and  exciting  cause  of  such  prevalent  and  some-  , 
times  discouraging  results  can  invariably  be  traced  to  faulty  and  miperfect 
adaptation  of  the  artificial  crown,  which  in  turn  reverts,  primarily,  to 
inadequate  and  unskilful  preparation  of  the  rcjot  supporting  it. 

As  clinical  experience  proves  most  conckisively  that  comfort  and 
permanency  depend  upon  a  conservation  or  re])roduction  of  the  natural 
conditions,  such  liabilities  decrease  of  course  in  proportion  to  the  degree 
of  accuracy  observed  in  the  operative  procedure. 

And  as  a  degree  of  accuracy  may  only  be  obtained  by  an  apprecia- 
tion of  the  significance  and  importance  of  the  requirements,  a  broad  com- 
prehension of  the  underlying  mechanical  principles,  and  a  thorough,  con- 
scientious execution  of  the  details  is  necessary. 

To  facilitate  this  the  consideration  of  the  subject  must  necessarily  be 
in  accordance  with  a  more  or  less  scientific  and  systematic  arrangement, 
in  the  order  of  the  practical  application  of  the  principles  and  technique 
involved. 

Prelitninarv  Requirements. 

When  it  has  been  determined  that  an  artificial  crown  is  indicated,  the 
first  essential  features  to  be  observed  should  always  include  a  considera- 
tion of  those  requirements  constituting  the  preliminary  operative  proce- 
dure incident  to  placing  the  roots  in  the  most  favorable  condition  possible 
for  the  subsequent  permanent  attachment  of  the  crown. 

The   very   first   detail   is   obviously  that  of  the 

CberapeutiCS.  therapeutic    treatment    necessary    in     securing     an 

aseptic  condition  of  the  root,  including  pulp  canals 
and  surrounding  tissues. 

This  should  invariably  precede  the  removal  or  destruction  of  any  of 
the  remaining  walls,  because  of  the  facility  which  their  retention  affords 
for  the  application  of  the  rubber  dam,  which  is  essentially  desirable  and 
advantageous  in  rendering  the  field  immune  from  secretions  while  med- 
icinal applications  are  being  made. 

After  the  removal  of  all  disintegrated  structure,  the  usual  remedial 
agencies  indicated  by  the  requirements  and  the  existing  conditions  should 
be  consecutively  applied,  until  thorongh  asepsis  of  sufficient  potency  to 
preclude  any  possibility  of  subsequent  disease  or  disintegration  is  obtained. 

When  this  has  been  successfully  accomplished,  the  pulp  canals 
should  be  thoroughly  filled  throughout  their  entire  length,  irrespective 


54 

of  the  style  of  crown  indicated,  and  the  root  filHng  then  temporarily  cov- 
ered and  protected  with  cement  to  exclude  the  deteriorating  influences 
of  moisture  during  its  hardening  and  crystallization. 

Teasibilitv  of  Devitalization. 

The  problem  of  the  feasibility  of  sacrificing  the  vitality  of  pulps  ii. 
teeth  which  are  to  be  subsequently  crowned  is  one  of  great  importance, 
and  is  a  portion  of  the  operative  procedure  incident  to  the  preparation  of 
such  teeth,  which  requires  the  most  conscientious  and  conservative  con- 
sideration. 

For  many  years  no  special  thought  was  given  to  this  feature,  and 
such  teeth  as  seemed  to  indicate  restoration  by  crowning  were  treated 
much  in  the  same  manner  as  though  fillings  were  to  be  inserted. 

The  frequency  of  subsequent  troublesome  manifestations,  however, 
including  the  ultimate  death  of  pulps  with  t'.ic  attending  consequences 
of  such  pathological  conditions  as  virulent  peridental  inflammations  and 
alveolar  abscesses,  have  since  caused  the  subject  to  be  more  carefully  con- 
sidered, until  it  is  now  most  generally  conceded  to  be  a  safer  precaution, 
in  a  great  majority  of  cases,  to  destroy  such  pulps  as  a  prophylactic  proce- 
dure as  v.ell  as  to  facilitate  the  necessary  mechanical  preparation,  when 
the  crown  is  to  entirely  cover  the  end  of  the  root. 

It  is  now  a  more  or  less  generally  acknowledged 

PbysiOlOglcal  belief  of  the  most  eminent  authorities  that  the  pulp 

Considerations.  j^  purely  a  formative  organ,  and  that  its  physiological 
function  terminates  with  complete  development  of  the  tooth ;  that  it  is 
not  necessary  to  its  vitality,  stability  and  longevity  after  maturity,  pro- 
viding that  the  pulp  cavity  is  perfectly  filled  ;  thus  there  seems  to  be  no 
good  reason  for  its  preservation,  taking  into  account  the  modern  aseptic 
means  of  removing  it  and  treating  and  filling  the  canals. 

Especially  is  this  true  where  a  crown  is  indicated,  because  the  abnormal 
encasing  of  the  tooth  so  as  to  practically  isolate  it  must  at  least  diminish 
the  external  influences  of  secretions  and  temperature  upon  the  nerve  and 
blood  supply  of  the  pulp ;  and  because  usually  such  teeth  have  already 
been  subjected  to  the  irritating  and  devastating  influences  of  caries,  each 
of  which  seems  but  to  invite  and  pave  the  way  for  ultimate  destructive 
processes. 

Other  deleterious  influences  may  come  from  the  irritating  action  of 
the  cements  used  in  mounting,  or  from  the  effects  of  the  shock,  or  over- 
stimulation induced  by  the  necessary  mechanical  preparation,  either  of 
which  may  often  prove  important  factors  in  rendering  such  teeth  sus- 
ceptible to  a  "slow  but  often  complete  and  unnoticed  destruction." 


55 

All  things  considered,  the  prophylactic  measure  seems  the  conserv- 
ative one,  and  as  modern  scientific  root  treatment  offers  no  palpable  ex- 
cuse for  subsequent  pathological  conditions,  it  seems  that  the  orthodox 
dogma  of  preservation  is  inapplicable  to  a  great  majority  of  cases, 
where  experience  and  judgment  teach  us  the  demand  for  a  perhai)S  more 
"radical"  but  manifestly  safer  procedure. 

The  contraindication  for  such  treatment  would  be  in  the  mouths  of 
patients  under  sixteen  years  of  age,  where  in  all  pro1)ability  complete  devel- 
opment of  the  tooth  had  not  yet  been  attained.  In  such  instances,  however, 
it  would  be  as  unwise  to  j^ass  the  crown  entirely  beneath  the  gum  as  it 
would  be  to  destroy  the  vitality  of  the  pulp,  unless  both  w  ere  necessary. 
And  after  fifty  years  of  age  the  necessity  for  such  treatment  is  often 
g'reatly  diminished  because  of  the  physiological  phenomena  of  the  gradual 
atrophy  of  the  pulp,  and  the  formation  of  secondary  dentine,  which  so 
lessens  the  sensitiveness  of  the  structure  as  to  admit  freely  of  the  neces- 
sary preparation,  while  reducing  the  probability  of  the  ultimate  occur- 
rence of  pathological  conditions  to  a  minimum. 

Occasional  exceptions  may  also  be  warranted  in  those  cases  of  ab- 
normal development,  faulty  enamel  formation,  extensive  abrasion  as  a 
result  of  attrition,  and  where  the  absence  of  adjacent  and  occluding  teeth 
makes  necessary  but  little,  if  any,  preparation,  but  such  indications  can 
only  be  governed  by  experience  and  judgment. 

Because   these    considerations    apply   more   par- 

mccbanical  ticularly  to  the  posterior  teeth,'  where  the  shell  or 

(Considerations.        telescope  crown  is  indicated,  and  where  the  removal 

of  a  considerable  portion  of    the    remaining  tooth 

structure  becomes  an  absolute  requirement,  the  destruction,  of  the  pulp  is 

usually  imperative  as  a  means  of   making  possible  and  facilitating  the 

necessary  preparation  in  the  diminution  of  the  cbronal  proportions  of  the 

natural  crown. 

^^'hen  the  vitality  is  preserved,  this  procedure,  always  exacting,  is 
ordinarily  so  difficult  that  it  must  be  either  perfunctorily  and  negligently 
performed,  or  else  the  patient  must  be  made  to  tolerate  an  exceedingly 
and  often  excruciatingly  painful  operation. 

Frequent  evidences  of  flagrant  indifference  and  negligence  are  so 
manifest  as  to  prove  conclusively  that  in  a  large  majority  of  cases  the  vig- 
orous efforts  necessary  to  secure  the  best  and  most  successful  results  may 
only  be  obtained  under  the  most  favorable  conditions. 

Creatment  of  l)ypertropl)y. 

In  instances  where  an  exuberant  growth  or  hypertrophy  of  pulp  or 
gum  tissue  is  present,  or  may  have  almost  entirely  covered  the  end  of  the 


56 

root,  some  difficulty  may  be  experienced  in  applying  the  dam  and  pur- 
suing the  necessar}^  course  of  treatment. 

Both  may  be  greatly  facilitated,  however,  by  the  immediate  excision 
and  removal  of  such  tissue  at  the  first  sitting,  and,  if  the  continuity  of  the 
root  be  destroyed  by  disintegration,  or  if  its  length  will  not  admit  of  the 
application  of  the  clamp  and  rubber  dam,  a  temporary  restoration  can  be 
easily  effected  by  adjusting  a  band  of  German  silver  closely  encircling 
the  circumference  of  the  root,  as  soon  as  the  suppression  of  the  hemor- 
rhage, by  the  use  of  styptics,  will  permit. 

Such  a  band,  if  properly  and  carefully  fitted  to  the  neck  of  the  root,, 
and  trimmed  so  as  to  have  no  sharp  or  irregular  edges,  and  not  to  in- 
terfere with  the  occlusion,  will  at  once  admit  of  the  application  of  the  dam 
by  adjusting  the  clamp  over  it,  and  may  remain  in  place  and  be  worn  with 
comfort  until  the  necessary  treatment  and  final  filling  of  the  canals  has 
been  accomplished. 

If  filled  flush  to  the  edge  with  temporary  stopping  at  the  end  of  each 
treatment,  it  further  serves  to  hermetically  seal  the  dressing  within  the 
root,  and  to  compress  the  tissues  so  as  to  afiford  a  free  exposure  of  the 
periphery. 


Tree  Exposure  of  tbe  Root 

During  the  process  of  treatment  in  all  badly  broken  down  roots  some 
means  should  alzvays  be  employed  to  compress  the  tissues  in  such  manner 
as  to  freely  expose  the  end,  which  greatly  facilitates  the  fitting  of  the 
band,  or  the  adjustment  of  the  crown,  and  materially  lessens  the  usual 
discomfiture  attending  the  operation. 

When  the  use  of  a  temporary  band  is  not  indicated,  or  seems  unneces- 
sary, the  same  advantages  may  be  gained  by  packing  temporary  stopping 
into  and  over  the  end  of  the  root,  and  under  the  free  margin  of  the  gum. 

If  the  root  is  too  shallow  to  anchor  it  securely,  it  may  be  so  retained 
by  packing  tightly  against  the  adjacent  teeth,  or  held  firmly  by  ligatures 
attached  to  them,  or  by  inserting  a  small  sharp  tack  through  it  and  into 
the  tooth  structure. 

In  instances  where  the  accumulation  of  gases  demand  some  vent,  a 
perforation  may  be  made  through  the  stopping  at  a  convenient  point. 

Care  should  also  be  exercised  to  prevent  undue  pressure,  which,  if 
existing  for  an  indefinite  time,  might  possibly  cause  injury  to  peridental 
membrane  or  surrounding  tissues,  as  a  result  of  protracted  lack  of  cir- 
culation. 


57 


Classification. 

The  principles  involved  in  the  necessary  preparation  of  roots  are 
governed,  of  course,  by  the  particular  style  of  crown  indicated,  and,  while 
crown  work  is  divided  into  tzvo  general  classes,  according  to  the  method 
of  attachment  employed,  a  variation  in  the  essential  details  of  their  indi- 
vidual construction  requires  that  each  class  be  subdivided,  and  that  the 
subject  be  considered  in  four  general  classes. 

In  order  to  meet  the  requirements  occasioned  by  this  variation,  each 
class  will  be  considered  separately,  and  are  as  follows : 


Preparation    for    shell    or    tele- 
scope crown. 

Preparation  for  shell  or  telescope 
crown  with  porcelain  facing. 


Preparation  for  band  and  dowel 
crown. 

Preparation     for     dowel     crown 
without  band. 


Preparation  for  Shell  or  telescope  Crown. 

The  detail  of  procedure  indicated  by  the  require- 
RCdUircmcntS.         ments  for  a  shell  or  telescope  crown,  because  of  be- 
ing   generally    confined    to    the    posterior    teeth,    is 
usually  the  most  difficult,  and  should  be  closely  observed. 

In  those  instances  where  the  ravages  of  exten- 
RCStOftltion  Of  sive  decay  have  caused  the  destruction  of  the  remain- 
€ontinuity.  ing  walls  of  the  natural  crown,  so  as  to  carry  the 

cervical  border  at  some  point  within  or  beyond  the 
free  margin  of  the  gum,  some  means  of  permanent  restoration  of  the  con- 
tinuity of  the  root  is  usually  advisable. 

This  prevents  the  possible  fracturing  of  unsupported  walls  during 
their  preparation ;  adds  materially  to  the  integrity  of  the  root ;  greatly 
facilitates  the  fitting  of  the  band,  and  overcomes  the  probability  of  sub- 
sequent disintegration  arising  from  an  imperfect  adaptation  of  the  band 
to  the  margins  of  deep  cervical  pockets. 

Such  restoration  can  usually  be  best  accomplished  with  amalgam,  the 
use  of  which  affords  a  better  opportunity  for  securing  a  close  adaptatior* 
between  it  and  the  margins  of  the  root,  with  the  assurances  of  a  greater 
degree  of  permanency. 

Where  the  edge  of  the  band,  however,  can  be  fitted  closely  to  the 
root  at  all  points  around  its  entire  circumference,  with  a  reasonable  de- 
gree of  certainty,  and  where  the  walls  are  weak,  the  use  of  cement  for 
this  purpose  is  preferable,  because  of  the  additional  support  rendered  by 
its  adhesive  qualities,  and  because  any  further  destruction  of  the  tooth 


58 

structure  for  the  purpose  of  securing  retention  is  unnecessary ;  but  when 
tlie. extreine  depth  of  the  marginal  edge  (Fig.  32)  makes  a  close  adapta- 
tion of  the  band  either  impossible  or  doubtful,  amalgam  should  be  used. 

In  using  amalgam  adequate  retention  must  be  secured  in  the  pulp 
cliamber,  or  root  canals  if  necessary.  A  thin  circular  matrix  of  German 
silver,  g.  34-36,  should  then  be  adapted,  and  so  shaped  as  to  make  the 
restoration  of  suitable  form  to  save  further  preparation.  After  adjusting 
tlais,  its  inner  surface  should  be  coated  with  vaseline,  oil,  or  any  lubricat- 


Fic^.32. 

ing  substance,  to  prevent  adherence  of  the  amalgam,  and  insure  its  easy 
removal  after  crystallization.  To  admit  of  and  facilitate  this  the  amal- 
gam should  never  extend  as  high  as  the  edge  of  the  band,  and  a  subsequent 
sitting  is  usually  necessary.      (Fig.  33.) 

In  roots  where  the  entire  crown  has  been  destroyed,  it  is  usually 
necessary  to  rebuild  and  restore  a  portion  of  it,  in  order  to  better  and 
more  securely  sustain  the  artificial  crown,  by  obtaining  greater  integrity 
between  it  and  the  root  at  the  line  of  junction.    This  may  be  easily  ac- 


complished by  adjusting  the  matrix,  and  firmly  inserting  a  screw-post 
into  the  most  accessible  canal,  additionally  fortified  with  cement  (Fig. 
34),  and  then  building  up  with  amalgam  to  the  desired  length  and  shape. 

The  diminution  of  the  natural  crown,  or  its  re- 
Diminution  of  maining  walls,  in  a  manner  favorable  to  the  require- 

i^OfOnal  Proportions,    ments,   is  frequently  a  very  difficult  procedure  be- 
cause of  the  usual  inequality,  in  teeth  of  normal  pro- 
portions, between  the  diameters  of  the  crown  and  the  cervix. 


59 

This  requires  and  necessitates  the  removal  of  considerable  tooth 
structure  in  order  that  the  circumference  may  be  reduced  at  every  point 
qcclusally,  and  at  the  uniform  expense  of  each  surface,  at  least  equal  to 
the  exact  dimensions  at  the  cervix. 

While  it  is,  of  course,  desirable  to  leave  as  much  as  possible  of  the 
riemaining  coronal  portions,  it  will  be  observed  from  the  illustrations 
("Fig.  35)  that  approximately  about  one-sixteenth  of  the  structure  from 
the  axial  walls,  and  the  occlusal  one-fourth  must  be  removed. 


Such  a  requirement  is  not  a  hypothesis,  but  a  physical  and  mechan- 
ical problem  which  must  necessarily  be  closely  observed,  in  order  that  it 
may  be  made  possible  for  the  band  to  approximate  a  close  adaptation  to 
the  normally  constricted  neck ;  and  to  admit  of  a  reproduction  of  the 
occlusal  surface  in  the  artificial  crown  possessing  sufficient  thickness  to 
withstand  the  influences  of  constant  attrition. 

To  further  increase  the  opportunities  for  securing  a  closer  continuity 
between  crown  and  root,  the  remaining  walls  should  not  merely  be  parallel. 


Fia.35. 


but  should  be  slightly  inverted,  so  that  the  band  may  fit  more  closely  as  it 
is  pressed  rootwise,  and  thus  prevent  its  edge  from  being  forced  into  the 
gum  tissue,  instead  of  under  or  within  the  frise  margin. 

This  requirement  is  indisputably  essential  when  the  crown  is  intended 
to  approach  or  pass  beneath  the  gum,  if  comfort  and  perm.anency  are  to 


6o 

be  obtained  from  the  operation,  and  is  one  of  the  strongest  arguments  in 
favor  of  the  devitalization  of  the  pulp. 

Owing  to  the  general  tendency  of  teeth  to  gravi- 

Paralkling,  tate  or  tip  toward  the  unoccupied  area  in  interrupted^ 

Gonocrfllns  or         arches  (Fig.  36),  in  their  preparation  for  bridgework 

DiOCrging  C<etb.       it  is  essential  to  observe  that  the  surfaces  of  eachi 

individual   root  presenting  toward   each  other,   are 

made  absolutely  perpendicular,  as  illustrated  in  Fig.  37. 

Such  a  condition  will  frequently  be  found,  and  no  matter  how  per- 


^y. 


36. 


^,37. 


fectly  each  individual  root  should  be  prepared,  the  presentation  of  per- 
pendicular lines  is  necessary  to  admit  of  the  adjustment  of  the  bridge^ 
after  completion. 

Operative  Procedure. 

As  this  portion  of  the  operation  is  particularly  trying  to  the  patient,, 
as  well  as  the  operator,  a  good  assortment  of  stones,  disks  and  burs,  kept 
sharp,  even-edged,  and  mounted  true,  is  essential,  and  all  unnecessary 
grinding  should  invariably  be  avoided. 

When  any  of  the  walls  of  the  tooth  remain  or  approximate  their  full 
length,  the  first  detail  should  be  to  undermine  the  enamel  to  the  desired 
point  by  cutting  away  the  dentine  with  a  sharp  bur.  Such  walls  may 
then  be  easily  broken  down  with  the  excising  forceps,  and  much  unneces-  ■ 


6i 

sary  grinding  thus  avoided.  The  surface  of  the  occlusal  end  should 
be  ground  smooth  with  a  thick-edge  stone.  The  buccal  and  lingual  walls 
may  be  reduced  with  a  thin-edge  stone  of  suitable  diameter,  in  which 
it  is  essentially  necessary  to  keep  the  revolving  stone  moving  upward  and 
downward  against  the  surface  of  the  tooth,  to  prevent  the  formation  of  a 
shoulder  or  ridge  at  any  point,  and  to  assure  a  uniform  reduction. 

After  these  walls  have  been  adequately  reduced,  the  trimming  of  the 
approximal  walls,  usually  the  most  difficult,  is  next  in  order.    When  they 


Ficj.3  8. 

remain  high  enough  to  afford  considerable  support  to  the  enamel,  grind- 
ing must  still  be  resorted  to,  as  the  cleavers  will  be  found  practically  use- 
less in  detaching  and  removing  it  unless  it  is  more  or  less  disintegrated. 

For  such  purposes  a  thin-edge  stone  or  diamond  disk  of  suitable 
diameter  may  be  used,  by  beginning .  from  the  occlusal  end,  at  a  point 
about  one-sixteenth  of  an  inch  from  the  periphery,  and  cutting  through 
on  a  slight  angle  until  the  interproximal  space  is  reached. 


f/a.3  9. 


A  small  cross-cut  fissure  bur  inserted  into  the  interproximal  space  at 
right  angles  to  the  teeth,  and  brought  occlusally  with  considerable  pres- 
sure against  the  root,  may  often  serve  as  a  valuable  supplement  to  the 
stone,  or  sometimes  answer  the  purpose  itself,  if  sufficient  care  be  exer- 
cised to  prevent  mutilating  the  adjacent  teeth,  which  may  often  be  pro- 
tected with  a  band  matrix. 

When  adjacent  teeth  are  absent,  the  procedure  is  less  difficult,  and 
may   be   accomplished    with   a   blunt   safe-edge   stone,   as    illustrated    in 


62 

Fig.  38,  or  a  stone  possessing  the  shape  of  an  inverted  cone.  The  latter  is 
'very  often  found  most  useful  in  reducing  the  surfaces  of  molars. 

If  the  remaining  walls  are  short,  and  the  enamel  is  somewhat  disin- 
tegrated, the  cleavers  may  be  found  very  useful. 

When  sufficient  diminution  of  the  structure  has  been  secured,  the 
sharp  corners  should  be  nicely  rounded  with  burs  and  sandpaper  disks, 
and  the  necessary  preparation  is  then  completed. 

The  degree  of  accuracy  thus  obtained  will  be  denoted  by  the  freedom 
and  facility  with  which  the  measurement  wire  may  be  detached  from  the 
root  after  being  twisted  taut,  and  the  buccal  and  occlusal  aspects  should 
present,  as  indicated  in  Fig.  39. 


Ficj.  ao. 


Preparations  for  Sbell  or  telescope  Crown  witb  Porcelain  Tacing. 

While  the  same  general  principles  apply  to  the 
K((tUiremcnt$.          necessary  preparation  for  a  shell  or  telescope  crown 
with  porcelain  facing,  and  the  same  detail  of  proce- 
dure is  indicated,  a  variation  is  required. 

This  variation  comprises  grinding  down  the  buccal  wall  sufficiently 
to  accommodate  the  presence  of  the  facing,  as  the  area  to  be  occupied  by 
it  must,  of  course,  be  gained  at  the  expense  of  the  remaining  root. 
(Fig.  40.) 

This  should  never  be  done,  however,  until  after  all  other  require- 
ments, as  before  outlined,  have  been  observed,  and  it  may  be  done  to 
even  better  advantage  after  the  band  has  been  fitted. 

Preparation  for  Band  ana  Dowel  £rown. 

The    requirements    of    root    preparation    for   9. 

K^dUiretiKlttS.         band    and    dowel    crown    are    similar    in    peripheral 

features  to  the  requirements  for  a  shell  or  telescope 


63 

crown,  but  differ  in  that  all  of  the  remaining  natural    crown    must,    of 
course,  be  sacrificed  to  more  nearly  approximate  the  gum  line. 

This  is  necessary  because  the  line  of  junction  between  crown  and* 
root  is  made  at  this  point  in  order  to  accommodate  the  artistic  and) 
esthetic  presence  of  a  porcelain  facing. 


Operative  Procedure. 

In  the  operative  procedure  incident  to  removing  the  remaining  por- 
tions of  the  natural  crown,  as  much  of  it  as  possible  should  be  cut  away 
and  broken  down  to  a  certain  point,  in  order  to  avoid  all  unnecessary 
grinding. 


Fi 


'T 


Fia.  0-2. 


In, the  incisors  and  cuspids  this. may  be  quickly 

excising  Tticiscrs       and   easily    accomplished   by  first   tindermining  the 

and  Cuspids.  remaining  enamel  with    a    bur,    and    then    cutting 

grooves  through  it  at  a  point  which,  when  the  crown 

is  excised,  will  leave  a  projecting  end  of  the  root  about  one-sixteenth  of 

an  inch  beyond  the  gum  line.     (Fig.  41.)  . 

Care  should  be  exercised  in  cutting  the  grooves  entirely  through  the 
enamel,  so  as  to  relieve  or  reduce  the  shock, .and. prevent  a  fracture  rootr 
wise.  The  beaks  of  the  excising  forceps  may  then  be  placed/in  th,' 
grooves,  and  the  crown  easily  and  safely  removed.  ...  ;• 

In    removing    the    remaining    portion    of    ,tl>e 
Excising  Bicuspids      crowns  of  bicuspids  and  molars,  the  grooves  and  exr 
and  ItlOlars.  cising  forceps  possess  the  same  advantages. 

In  their  use,  however,  any  remaining  continuity 
between  buccal  and  lingual  walls  must  also  be  first  attacked  with  a  bur  to 
-destroy  their  integrity.  (Fig.  42.)  This,  in  conjunction  v/ith  grooves, 
.will  facilitate  their  excision  without  shock  or  danger  of  fracture. 


64 

The  remaining  ledge  of  enamel  upon  this  pro- 

K^tnoval  Of  €namcK     jecting  end  of  the  root,  which  has  been  purposely 

retained,  for  the  time,  must  then  be  removed  in  order 

tOfbring  the  greatest  diameter  beneath  the  gum,  where  the  line  of  junction 

between  band  and  root  is  to  be  made.     This  can  be  best  accomplished  by 

the  use  of  enamel  cleavers  designed  for  the  purpose. 

The  use  of  enamel  cleavers  of  any  design  may 
4I$C  Of  CttantCl         or  may  not  be  of  a  desired  degree  of  effectiveness; 
aUWitS,  according  to  the  manner  in  which  they  are  manipu- 

lated,   and    the    easy    and    expeditious    removal    of 
enamel  depends  entirely  upon  their  proper  manipulation. 

The  edge  of  the  cutting  blade  of  the  instrument  must  be  placed  above 
ihe  enamel  and  held  at  the  proper  angle  in  its  relation  to  the  surface  of 


Ficj.43, 


Flxj.Q-^. 


the  root;  and  a  fulcrum  must  be  established  to  facilitate  the  application 
and  exertion  of  the  necessary  force  to  secure  the  destruction  of  what  is 
usually  a  very  dense  attachment. 

The  adjacent  teeth,  when  present,  will  serve  as  a  means  of  estab- 
lishing such  a  fulcrum ;  and  in  their  absence  the  same  may  often  be  se- 
•cured  by  placing  a  smooth  piece  of  soft  wood  or  rubber,  of  sufficient 
thickness,  against  the  incisal  or  occlusal  ends  of  remaining  teeth,  or  the 
:gums,  against  which  the  thumb  may  rest  as  a  means  of  affording  oppor- 
tunity for  securing  purchase  and  leverage. 

While  various  styles  of  instruments  have  been  suggested  for  this 
purpose,  those  designed  by  Dr.  C.  S.  Case  (Fig.  43)  will  be  found  admir- 
ahly*  adapted  to  upper  anterior  roots ;  and  those  designed  by  Dr.  A.  G. 


65 

Johnson  (Fig.  44)  are  especially  useful  for  posterior  and  lower  roots, 
though  adapted  for  universal  use.  The  manner  of  holding  them  in  the 
hand  and  securing  purchase  upon  adjacent  teeth  is  illustrated  in  Fig.  45. 

After  all  enamel  has  been  removed,  the  pe- 
PCfiphCral  Crlltimlllfl*  riphcry  of  the  root  should  be  made  smooth  and  to 
present  a  perpendicular  line,  as  indicated  before  and 
after  in  Fig.  46.  This  can  be  easily  accomplished  with  a  small  fissure 
bur;  or,  a  set  of  trimmers  suggested  by  Dr.  J.  H.  Prothero  (Fig.  47),  or 
the  "Root  Reducer,"  manufactured  by  the  S.  S.  White  Co.  (Fig.  48), 
both  of  which  are  designed  for  this  purpose,  and  may  be  found  useful. 


Fia.  0.6. 

Before  considering  the  final  shaping  of  the  end 
Shaping  Basal  or  basal  surface  of  such  roots,  it  may  be  well  to  em- 

Surface.  phasize  that  they  have  been  purposely  left  projecting 

somewhat  beyond  the  gum,  as  indicated,  until  the 
peripheral  preparation  is  complete,  because  of  thus  materially  facilitating 
the  removal  of  enamel,  and  the  subsequent  taking  of  the  measurement  and 
fitting  of  the  band,  and  for  the  reason  that  this  freely  exposed  and  project- 
ing surplus  end  serves  to  retain  the  wire  until  an  accurate  measurement 
may  be  secured,  and  to  conform  the  hand  to  the  proper  shape  and  guide  it 
to  place  in  fitting. 

The  fitting  of  the  band  is  thus  made  practically  free  from  discom- 
fiture to  the  patient,  and  easy  for  the  operator,  and  after  it  has  been  fitted 
and  trimmed  to  the  desired  width,  the  root  should  then  be  cut  down  to 
the  proper  form  of  base. 

The  shape  given  the  basal  surface  of  the  root  is  of  much  importance, 
and  particularly  in  the  upper  anterior  teeth,  where  the  requirements  make 
it  desirable  to  leave  the  lingual  edge  somewhat  longer  than  the  labial  in 


66 


order  to  afford  greater  mechanical  resistance  to  the  stress  naturally  im- 
■  posed,  and  to  carry  the  labial  edge  a  trifle  beneath  the  gum,  so  that  the 
band  or  cap  may  be  invisible,  and  the  neck  of  the  porcelain  facing  placed 
in  close  proximity  to  the  gum  line. 

Compliance  with  these  mechanical  and  esthetic  requirements  results. 
of  course,  in  beveHng  the  end  of  the  root,  as  indicated  in  Fig.  49  (which 


/ii  fr^'Mi 


//  , 


^^^"f^Y^ 


f/a.SO. 


Ficj.Sf. 


is  the  common  practice),  or  in  shaping  it  on  a  slight  and  gradual  inclined 
plane,  as  illustrated  in  Fig.  50.  The  latter  is  the  best  and  preferable 
■preparation,  because  of  affording  greater  opportunities  for  the  adapta-* 
tion  of  the  cap  and  facing  without  causing  undue  prominence  at  the  neck 
(a  common  fault  with  artificial  crowns),  and  with  a  minimum  of  grinding 
of  the  facing,  and  a  maximum  of  strength  in  the  crown. 


,;'«Wl\i\l 


ncj,5p. 


This  can  be  best  accomplished  with  a  flat-edge  carborundum  or 
"vulcan"  carborundum  stone  (Fig.  51),  kept  wet  when  using  (the  latter 
having  the  advantage  of  wearing  true) ,  until  the  gum  line  is  reached, 
when  the  Ottolengui  root- facers  (Fig.  52)  are  most  useful  in  cutting  it 
beneath  the  gum  on  the  labial  or  buccal  edges,  without  lacerating  Mie 
tissues.    These  should  be  of  the  "safe-sided"  variety,  and  are : made  iin 


67 

three  sizes,  to  accommodate  the  size  of  root  and  the  space  between  adja- 
cent teeth,  and  should  be  used  with  extreme  care,  as  they  cut  rapidly. 

In  the  preparation  of  bicuspid  and  molar  roots,  where  the  stress  is 
direct,  it  is  usually  desirable  to  leave  the  basal  surface  almost  fiat,  as  in- 
dicated in  Fig.  53.  This  allows  more  opportunity  for  securing  strength 
in  the  finished  crown,  and  adds  to  the  possibilities  for  its  closer  adapta- 
tion and  for  an  observance  of  the  more  artistic  and  esthetic  requirements. 

In  no  instance,  however,  should  this  final  preparation  be  made 
until  the  hand  has  been  fitted. 


Preparation  for  Dowel  Crown  without  Band. 

In  the  preparation  of  roots  for  the  dowel  crown  without  band,  the 
same  procedure  applies  to  the  removal  of  the  remaining  natural  crown, 
as  indicated  in  the  preparation  for  this  style  of  crown  with  a  band. 

After  the  remaining    portions    of    the    natural 
R((SUircmcnt$.         crown  have  been   sacrificed,   however,   the  essential 
features  differ  somewhat  in  the  shape  given  to  the 
basal  surface,  and  in  that  the  removal  of  enamel,  or  any  peripheral  prep- 
aration, is,  of  course,  entirely  unnecessary. 

Operative  Procedure. 

As  the  permanency  and  success  of  such  crowns  depend,  to  a  great 
extent,  upon  the  degree  of  accuracy  secured  in  the  adaptation  to  the  root, 
its  end  must  be  so  shaped  as  to  render  the  opportunities  for  a  close  adapta- 
tion most  favorable. 

In  the  preparation  for  that  style  of  crown  in 

Tnseparable  Dowels,     which  the  dowel  is  an  integral  part  (as  the  Logan 

crown),  the  form  given  to  the  basal  surface  should 

be  exactly  as  indicated  before,  in  Fig.  50,  and  the  procedure  is  identical, 

excepting  the  removal  of  enamel. 

This  preparation  becomes  necessary  because  the  presence  of  an  im- 
movable dowel  makes  the  grinding  of  the  crown  to  adaptation  with  the 
root  somewhat  difficult  at  best,  but  which  is  facilitated,  of  coiu'se,  by  hav- 
ing the  root  present  as  smooth  a  surface  as  possible.  The  labial  surface 
may  then  be  brought  in  contact  with  the  gum  margin,  which  is  desirable 
for  esthetic  reasons,  while  the  line  of  junction  upon  the  lingual  surface 
will  be  in  accord  with  prophylactic  measures  in  being  rendered  self- 
cleansing  by  exposure  to  the  secretions  and  movements  of  the  tongue.    ' 


68 

The  difficulty  in  adapting  such  crowns  because 
Separabk  DCWdS.      of  the  interference  of  the  dowel  in  grinding,  consti- 
tutes the  advantages  possessed  and  afforded  by  those 
with  separate  dowels,  such  as  the  Davis  crown. 

Where  it  is  intended  to  construct  the  crown  with 
Plate  and  D0W(1«       plate  and  dowel  as  separate  parts,  to  be  subsequently 
attached  with  solder,  and  where  the  close  adaptation 
of  the  plate  may  be  secured  by  swaging  or  burnishing,  the  lingual  por- 
tion should  also  be  beveled  almost  to  the  gum  line.     (Fig.  54.) 

By  thus  saddling  the  end  of  the  root,  greater  mechanical  resistance 


is  offered  to  the  displacement  of  the  crown,  while  the  prophylactic  require- 
ments are  secured  in  a  better  adaptation  of  the  surface,  and  a  closer  ap- 
proximation of  the  edge  of  the  plate  to  the  periphery  of  the  root. 

In  roots  which  present  a  concave  base  as  the  re- 

ProUCtlon  Of         suit  of  extensive  decay,  the  walls  should    first  be 
Unsupported  malls,     ground  down  until  smooth,  and  as  dense  as  the  mar- 
ginal outlines  noted  will  admit,  and  then  supported 
with  a  suitable  material. 

When  the  continuity  remains  unbroken,  cement  will  best  answer  the 
purpose,  but  if  some  restoration  seems  necessary,  the  use  of  amalgam  is 
usually  indicated  for  the  reasons  mentioned. 

As  mechanical  retention  is  frequently  impossible,  in  these  roots, 
some  difficulty  may  be  experienced  in  anchoring  it  where  its  use  is  indi- 
cated, but  this  may  be  accomplished  by  first  thoroughly  roughening  or 
serrating  the  dentine  with  a  wheel-bur,  and  then  flowing  over  it  a  thin 
coating  of  cement  and  immediately  packing  the  amalgam  to  place. 

The  cement  thus  aids  materially  in  securely  anchoring  the  amalgam, 
and  a  more  permanent  restoration  is  often  afforded. 

In  very  extensive  decay  these  walls  may  sometimes  be  better  sup- 


69 

ported  by  forming  the  base  of  the  crown  itself  to  closely  fit  them,  so  as  to 
offer  the  necessary  protection  when  mounted  with  cement. 

Preparation  of  €anal$. 

The  preparation  of  the  canal  for  the  reception  of  the  dowel  should 
always  be  the  last  procedure,  and  is  of  special  significance  since  the  dowel 
plays  such  an  important  part  in  the  retention  and  stability  of  this  style  of 
crown. 

The  necessary  preparation  consists  in  enlarging' 

Ke(|Uireincnt$.         them  sufficiently  to  receive  a  dowel  proportionate  in 
sise  zvith  the  diameter  and  probable  length  of  the 
root,  and  consistent  zvith  the  requirements  of  the  crozcn.       Any  further 
enlargement  and  destruction  of  tooth  structure  is  injudicious  and  unneces- 
sary. 

One  dowel  is  sufficient  to  support  any  crown,  providing  that  it  may 
extend  into  the  root  a  depth  equal  to  the  length  of  the  crown  (Fig.  55), 


which  is  a  mechanical  requirement,  and  possess  strength  enough  to  with- 
stand the  stress. 

In  upper  first  bicuspid  and  in  molar  roots,  however,  if  the  probable 
length  or  constriction  of  the  root  precludes  this,  two  may  be  used. 

After  first  so  determining  the  size  of  dowel  indi- 

OpttMiVi  Procedure,    cated,  or  to  be  used,  in  the  individual  case,  the  canal 

should  then  be  enlarged  to  receive  it.     A  twist  drill 

or  sharp  round  bur  approximating  the  same  diameter  as  the  dowel  should 

then  be  selected,  and  the  canal  reamed  out  to  adequate  proportions. 

In  most  instances  it  is  desirable  to  extend  the  opening  into  the  canal 
somewhat  lingually.  in  order  to  permit  the  dowel  to  pass  through  the 
cap  at  a  point  which  will  carry  its  projecting  and  surplus  end  out  of  the 
way,  so  as  not  to  interfere  with  the  adjustment  of  the  neck  of  the  facing 
to  proper  relation. 

Considerable  care   should   be  exercised,   especially  in  bicuspid  and 


JO 

constricted  roots,  to  avoid  drilling  through  the  sides  of  the  root,  as  such 
perforations  usually  cause  much  trouble,  and  may  often  result  in  the  loss 
of  the  root. 

For  this  reason  the  round  bur  is  considered  the  best  and  safest  means 
of  enlarging  canals,  because  if  of  a  proper  size,  and  carefully  guarded, 
as  it  approaches  the  periphery  an  immediate  response  will  be  manifested 
from  its  approaching  proximity  to  the  peridental  membrane,  in  ample 
time  to  cause  cessation  of  drilling  and  prevent  perforation  of  root. 


Creatttient  of  Perforated  Koots. 

The  presentation  of  perforations  through  the  root,  whether  from 
accidental  causes  or  as  the  result  of  caries,  is  usually  a  most  aggravating 
state  of  affairs,  and  calls  for  much  painstaking  effort  to  again  place  such 
a  root  in  condition  to  remain  permanently  comfortable. 

A  hermetical  and  non-irritating  seal  is  required,  for  which  purpose 
soft  gold  foil,  tin  foil,  cement,  white  paraffin  and  gutta  percha  are 
generally  used. 

While  all  possess  some  good  qualities,  the  use  of  chemically  pure  tin 
foil  is  most  universally  successful. 

When  these  cases  present,  all  septic  and  inflamed  conditions  of  im- 
mediate and  surrounding  tissues  should  first  be  relieved  by  the  proper 
medicinal  applications.  A  small  cone  of  chemically  pure  tin  foil,  about 
No.  4  thickness,  should  then  be  rolled,  and  inserted  into  canal,  until  one 
end  is  passed  through  the  perforation.  With  a  smooth,  blunt,  root  canal 
plugger,  the  remaining  portion  of  the  cone  should  be  gently  packed 
against  the  walls  over  and  surrounding  the  perforation,  and  then  small 
pellets  of  slightly  moistened  cotton  should  be  packed  into  the  canal  to 
burnish  the  tin  to  close  adaptation. 

Upon  the  removal  of  the  cotton  the  tin  may  be  protected  and  held  in 
place  by  covering  with  chloro-percha  and  filling  the  root  with  cement. 

When  such  treatment  becomes  necessary  before  filling  the  canals, 
their  location  may  be  preserved  to  admit  of  same  by  the  insertion  of  a 
broach  into  each,  the  subsequent  removal  of  which  will  leave  them  still 
accessible  for  further  treatment  and  final  filling,  through  the  open- 
ings thus  made. 

The  use  of  tin  is  preferable  to  other  materials,  because  it  is  easily 
adapted,  even  in  the  presence  of  moisture,  and  is  absolutely  non-irritating, 
and  offers  a  still  greater  advantage  in  the  hermetical  sealing  afforded  by 
the  subsequent  formation  of  the  oxide,  which  chemical  action  is  induced 
by  contact  with  the  moisture  of  the  tissues. 


Crcatmcnt  of  TractureJ  Roots. 

The  not  infrequent  presentation  of  fractured  roots,  and  the  difficul- 
ties usually  encountered  in  their  treatment,  require  a  definite  knowledge 
of  the  various  means  employed  to  restore  and  preserve  their  usefulness, 
and  a  delicacy  and  dexterity  of  manipulation  in  the  procedure. 

In   the  posterior  teeth  these  conditions  usually 
Posterior  Ccctb>        result  from  overstrained  or  undue  masticatory  force 
upon  such  teeth  as  may  have  been  weakened  by  the 
presence  of  extensive  decay,  or  very  large  fillings,  involving  the  approx- 
imal  and  occlusal  surfaces,  and  causing  a  longitudinal  fracture  of  the  re- 
maining crown  and  root. 

Such  fractures  usually  extend  from  mesial  to  distal  surfaces,  separat- 
ing the  buccal  from  the  lingual  cusps,  and  may  often  be  successfully 
treated  and  permanent  usefulness  restored  by  crowning  the  root. 

When  such  a  course  seems  indicated,  the  first  procedure  should  be  the 


Ficj.  56. 

thorough  removal  of  all  loose  particles,  by  freely  washing  and  flooding  the 
tooth  with  tepid  water,  until  a  perfect  and  close  approximation  of  the 
parts  may  be  secured. 

This  approximation  should  then  be  securely  retained,  temporarily, 
until  permanent  fixation  may  be  obtained  by  mechanical  means. 
This  may  be  accomplished  by  using  well  annealed  German  silver,  or  or^ 
dinary  silver  suture  wire,  from  23  to  26  g.,  which  should  be  passed  around 
the  circumference  of  the  tooth  at  the  neck,  and  the  ends  then  twisted 
tightly  together. 

The  German  silver  wire  is  preferable  because  of  admitting  of  greater 
strain  without  breaking,  and  if  therapeutic  treatment  is  necessary  it 
may  then  proceed  until  the  tooth  and  adjacent  tissues  are  placed  in  favor- 
able condition. 

The  mechanical  procedure  then  necessary  to  firmly  and  permanently 
anchor  the  parts  is  governed  by  the  extent  of  structure  possessed  by  each 
independent  portion.  • 


72 

If  enough  remains  of  each  portion,  they  may  be  securely  attached  by 
cutting  dovetail  grooves  in  each,  and  then  flowing  a  thin  layer  of  cement 
over  the  entire  interior  surface,  thus  utilizing  its  adhesive  properties,  and 
then  filling  with  amalgam.     (Fig.  56.) 

When  the  latter  has  become  thoroughly  craystallized,  the  wire  may 
be  removed,  and  the  tooth  carefully  shaped  for  the  reception  of  the  crown. 
When  insufficient  structure  in  one  of  the  parts  precludes  this  procedure, 
the  desired  result  may  be  accomplished  by  first  wiring  securely,  and  then 
adjusting  the  rubber  dam  and  completely  filling  the  tooth  with  thin 
cement. 

If  the  presence  of  moisture  is  prevented,  the  adhesive  properties  of 
the  cement,  in  conjunction  with  the  wire  around  the  neck,  will  usually 
retain  the  parts  until  the  tooth  has  been  shaped,  if  care  be  exercised.  In 
this  particular,  the  stone  should  ahuays  revolve  toward  the  fracture  in 
order  to  prevent  displacement. 


Fiq.  51. 


The  wire  may  then  be  removed,  and  the  crown  fitted  and  mounted. 

Such  fractures  in  the  anterior  teeth  usually  oc- 

flntcrlor  CCCtb.        cur  as  the  result  of  a  blow  or  other  accident ;  or  from 

the  stress  of  mastication  upon  an    artificial    crown 

offering  no  protection  against  such  strain  and  perhaps  mounted  upon  a 

root  already  weakened  by  too  ext^isive  or  injudicious  enlarging  of  the 

canal  for  the  reception  of  the  dowel. 

When  the  fracture  does  not  extend  b€;yond  the  border  of  the  alveolus 
to  any  appreciable  extent,  it  is  usually  best  to  remove  the  loose  portion, 
compress  the  tissues  with  gutta  percha,  and  restore  with  amalgam.  Or" 
if  the  necessary  retention  is  not  possible,  the  base  of  the  crown  may  be 
closely  adapted  to  the  root,  and  the  restoration  made  with  the  crown. 

When  the  fracture  extends  beyond  the  alveolus,  however,  it  is  usually 
desirable  to  secure  fixation  and  retain  the  loosened  portion,  in  order  to 
prevent  the  resorption  following  its  loss. 

This  may  be  accomplished  by  cementing  and  wiring  until  sufficient 
preparation  can  be  made  to  admit  of  the  adjustment  of  the  crown. 


7Z 

If  each  portion  possesses  sufficient  structure,  additional  strength  may 
often  be  secured  in  their  fixation  by  the  use  of  an  uitradoilal  band. 

Where  the  length  and  thickness  of  the  fractured  part  may  seem  ta 
indicate  such  a  procedure,  the  parts  should  first  be  tightly  wired,  as  sug- 
gested, and  then  a  circular  groove  trephined  a  consistent  depth  through 
the  thickest  part  of  each,  into  which  a  band  may  be  subsequently  fitted 
(Fjg-  57) ;  by  the  use  of  a  very  simple  outfit  suggested  by  Dr.  B.  J. 
Cigrand.  When  the  band  has  been  adjusted  to  the  groove  and  ground 
smooth  with  the  basal  surface  of  the  root,  a  firm  secure  fixation  of  the 
parts  is  insured,  and  the  wire  may  then  be  removed  and  the  crown  ad- 
justed. 

While  some  little  suppuration  and  trouble  may 
ProanoslS.  be  subsequently  present  as  a  result  of  reuniting  frac- 

tured roots,  it  should  give  no  unnecessary  appre- 
hension because  if  properly  treated,  and  absolute  immobility  has  been 
secured,  it  is  usually  of  but  temporary  nature,  and  many  roots  so  treated 
seem  permanendy  restored  to  usefulness,  indicating  a  very  favorable 
prognosis. 


€De  Sbell  or  telescope  grown. 


CHAPTER   VII. 

Indications,  Contraindications,  Requirements :  Telescoping  Portion,  Occlusal 
End,  Methods :  Sectional  Method,  Procedure ;  Measurement,  Bands ;  Width, 
Length,  Soldering,  Fitting,  Contouring,  Occluding  Bite,  Impression.  Articulators. 
Processes  for  Cusp  Formation,  Carved  Cusp  and  Special  Die  Methods.  Procedure ; 
Swaged  Cusps,  Mould,  Dies,  Swaging,  Adjusting  Cusps,  Soldering  Cusp,  Finishing. 
Solid  Cast  Cusps.  Cusp  Formation  without  Models.  Use  of  Ash's  Crown  Swaging 
Device.  Die  and  Die-Plate  Methods;  Individual  Dies,  Die-Plates;  Application,  Ad- 
justing With  Models.  Adjusting  Without  Models.  Hollingsworth  System ;  Appli- 
cation. Millett's  System,  Application.  Lowry  System ;  Application.  Baird  System ; 
Application.  Seamless  Method:  Advantages.  Disadvantages;  Time,  Strength, 
Adaptation.  Detail  of  Construction;  Primary  Band,  Bite  and  Impression,  Prepar- 
ing Model,  Casting  Flasks,  Dies,  Forming  Blanks,  Swaging,  Adapting  and  Re-en- 
forcing. Reverse  Process:  Advantages,  Disadvantages,  Procedure;  Original 
Model,  Mould,  Swaging-Model,  Blanks,  Swaging,  Methods,  Scott's  Method,  Finish- 
ing. Application  to  Separated  Molar  Roots ;  Procedure,  Bands,  Cusps.  Applica- 
tion to  Individual  Roots.  Cantilever  Bridges.  Application  of  Amalgam :  With 
Band,  Without  Band.  Application  to  the  Anterior  Teeth :  Indications,  Procedure ; 
Adaptation  to  the  Mouth.  Adaptation  to  Models.  Carving  and  Swaging.  Die- 
plate  Methods;  Lowry  and  Millett  Systems;  Hollingsworth  and  Baird  Systems. 
Seamless  Method :  Reproductions.  Dowels.  Ready-made  Forms.  Removing  and 
Repairing;  Crown  Slitting  Forceps.     Preserving   Continuity   of   Bands.      Repairing. 


Brief  reference  has  already  been  made  to  the  history  and  usefulness 
of  the  gold  shell  or  telescope  crown,  and  to  this  style  of  crown  as  having 
been  one  of  the  early  achievements  in  the  preservation  of  badly  decayed 
teeth  or  roots,  and  the  restoration   to   their   former  functional   activity. 

Regardless  of  the  progress  and  development  of  crown  work  in  gen- 
eral, however,  and  irrespective  of  the  esthetic  and  hygienic  advantages 
of  porcelain  work,  this  style  of  crown  is  still,  and  probably  always  will  be, 
one  of  the  very  best  means  and  methods  of  subserving  the  requirements. 
Indeed,  when  their  application  is  indicated,  and  when  the  adaptation  and 
construction,  by  whatever  method  chosen,  is  practically  and  skilfully 
executed,  no  other  one  method  of  procedure  seems  to  offer  so  great  an 
opportunity  for  the  serviceable  and  permanent  reproduction  of  the 
normal  condition. 


75 

As  a  natural  consequence,  and  because  of  the  time-proven  value  of  a 
method  affording  such  opportunities  and  possessing  the  possible  quali- 
ties of  strength  and  indestructibility  to  so  great  an  extent,  many  roots  have 
been  permanently  saved  and  made  useful  that  would  otherwise  have  beai 
lost;  bridge-work,  both  fixed  and  removable  in  character,  has  devel- 
oped and  become  practical ;  and  yet  the  esthetic  and  artistic  possibilities  of 
modern  prosthesis  have  been  most  flagrantly  abused  by  injudicious  use, 
and  indiscriminate  application. 

If  dentistry  is  to  become  universally  acknowledged  as  a  profession 
embracing  a  field  of  dignified  and  scientific  pursuit,  and  if  dental  pros- 
thesis is  ever  to  be  accorded  the  recognition  and  distinction  of  an  art,  to 
which  the  scope  of  its  possibilities  entitle  it,  the  somewhat  common  prac- 
tice of  placing  gold  crowns  on  teeth,  within  the  range  of  vision  in  the 
mouth,  violating  all  traditions  of  art,  must  be  considered  as  degrading, 
and  should  be  most  vigorously  condemned. 

No  matter  how  skilfully  the  operation  may  be  made,  or  how  perfect 
the  result  obtained,  such  evidences  of  artificial  handiwork  whenever  prom- 
inently conspicuous  are  an  ofifense  to  art,  culture  and  refinement. 

As  a  result  of  the  appreciation  by  the  laity  of  more  artistic  endeavor, 
and  their  education  at  the  hands  of  those  conscientious  enough  to  exercise 
their  dtity,  the  request  for  such  work  is  now  so  limited,  and  so  few  will 
even  tolerate  them,  that  the  pernicious  practice  is  of  necessity  confined 
mostly  to  either  unscrupulous  charlatans,  or  to  those  who  wilfully  cater  to 
a  perverted  taste  and  a  barbaric  vanity. 

As  many  teeth  requiring  artificial  crowns,  how- 
Tndications.  ever,  are  beyond  the  range    of   vision,    gold    crowns 

may  often  be  used  without  objection,  and  to  the  best 
possible  advantage. 

Their  application  is  indicated,  principally  in  restoring  the  roots  of 
molars,  and  occasionally  of  second  bicuspids,  but  rarely  anterior  to  them.    - 

In  cases  of  close  occlusion,  where  the  cusps  of  the  opposing  teeth 
when  brought  into  direct  occlusion  afford  but  little,  if  any  opportunity  for 
securing  sufficient  strength  with  any  style  of  porcelain  crown ;  and  on 
roots  so  short,  disintegrated  and  weakened  as  to  require  support  and  resto- 
ration with  amalgam,  especially  in  the  mouths  of  men  where  their  pres- 
ence may  not  be  conspicuous  because  of  the  beard,  their  application  to  the 
first  bicuspids  may  be  sometimes  permissible;  also  in  the  preparation  of 
bicuspids  which  are  to  serve  as  abutments  for  bridgework,  where  it  seems 
advisable  to  allow  the  natural  crown  to  remain  as  long  as  possible,  in 
order  to  afford  greater  integrity  in  the  attachment  of  the  artificial  crown, 
and  thus  secure  increased  mechanical  resistance  to  the  stress  imposed 
upon  the  bridge. 


76 

-    -  Anterior  to  the  molars,  however,  and  particu- 

Contraindications.  larly  in  the  mouths  of  women,  their  appHcation  is 
usually  contraindicated  in  view  of  the  more  artistic 
means  available.  Any  exceptions  should  be  based  only  upon  a  conscien- 
tious consideration  of  the  existing  conditions  and  practical  requirements 
of  the  case ;  and  their  application  to  the  incisors  and  cuspids,  in  any  event, 
should  be  regarded  as  an  unpardonable  offense. 

KeQUirentetits. 

The  requirements  for  this  style  of  crown  do  not  dift'er  essentially 
from  those  of  crown  work  in  general,  as  previously  outlined.  Whenever 
and  wherever  employed,  they  should  be  constructed  of  a  material  thick 
and  heavy  enough  to  possess  adequate  strength  when  finished,  and  suffi- 
ciently high  in  karat  to  withstand  the  chemical  action  of  the  secretions. 

The  band  or  that  portion  which  telescopes  the 
tClC$CCping  Portion,  end  of  the  root  should  fit  closely  around  the  entire 
circumference ;  pass  a  short,  but  tmiform,  distance 
beneath  the  gingival  border  of  the  gum,  and  possess  a  smooth  rounding 
edge  so  as  to  offer  no  possible  irritating  influence  to  the  tissues  surround- 
ing it.  It  should  also  be  contoured  to  typical  form,  restore  the  points  of 
contact,  and  preserve  a  proportionate  and  symmetrical  alignment,  with 
the  adjacent  teeth. 

The    cusps    forming    the    occlusal    end    should 
j^        Occlusal  €nd.         mimic  or  approach  a  typical  reproduction  of  the  indi- 
vidual tooth ;  restore  the  normal  occlusion  by  contact 
with  opposing  teeth  at  several  points,  and  offer  no  interference  to  the  lat- 
eral motion  of  the  jaw  in  the  various  movements  of  articulation. 

They  should  also  be  deep  and  sharp  enough  to  aid  in  the  act  of  mas- 
tication, and  of  sufficient  thickness  to  withstand  constant  and  continued 
attrition. 

A  very  common  fault  with  a  large  majority  of  these  crowns  is  the- 
presentation  of  a  more  or  less  smooth  and  uninterrupted  masticating  sur- 
face. Such  a  condition  precludes  the  proper  mastication  of  food,  and 
minimizes  the  possibilities  of  service  and  usefulness,  which  may  be  easily, 
obtained,  and  which  qualities  such  substitutes  for  the  natural  condition 
should  always  possess. 

methoas. 

The  general  usefulness  of  this  style  of  crown  has  resulted  in  the 
presentation  from  time  to  time  of  an  innumerable  variety  of  methods  and 
systems  for  their  construction.  - 

The  degree  of  skill  possessed  by,  and  the  personal  preference  of  oper-- 


77 

ators  enter  into  the  use  of  all  of  them  to  such  an  extent  as  to  have  so  far 
prevented  the  adoption  of  any  particular  one  as  a  universal  system. 

Two  general  methods  of  construction  are  employed — the  Sectional 
and  the  Seamless,  and  each  has  many  diversified  processes. 

The  sectional  method,  wherein  the  band  and 
Sectional  method,  cusp  are  made  separately  and  subsequently  united,  is 
the  most  commonly  used.  This  procedure  seems  to 
afiford  more  absolute  accuracy  in  securing  adaptation ;  even  better  oppor- 
tunities for  the  reproduction  of  the  necessary  contour ;  consumes  less  time, 
and  admits  of  the  use  of  a  heavier  gauge  of  gold  throughout  the  construc- 
tion of  the  crown.  These  important  advantages  cause  it  to  be  readily 
accepted  as  the  most  universally  successful  method. 

The  joint  made  in  the  union  of  band  and  cusp  offers  no  objectionable 
features,  and  in  no  way  interferes  with  artistic  possibilities,  if  the  edges 


FJq.68. 


of  each  are  closely  and  perfectly  approximated,  and  the  union  made  with 
a  solder  closely  resembling  the  gold  in  color,  and  sufficiently  high  in  karat 
to  withstand  the  chemical  action  of  the  secretions  without  subsequent 
discoloration. 

In  the  procedure  incident  to  the  mechanical  con- 

Proccdurc.  struction    of   a    crown    possessing    a    band    by    any 

method,  the  first  detail  is  obviously  that  of  securing  a 

true  measurement  of  the  diameter  of  the  root  to  serve  as  a  positive  guide 

in  obtaining  a  band  of  accurate  dimensions. 

For    this    purpose    wire,    thin,    narrow    copper 
measurement.         strips,   and  waxed   floss  are  used.      Bessemer  steel 
wire,  about  No.  32,  is  preferable,  however,  because  of 
being  easier  to  adjust  and  handle,  and  more  reliable. 


.        78 

It  should  be  cut  in  suitable  length,  made  in  circular  form,  some- 
what larger  than  the  root,  and  the  ends  then  securely  attached  in  a  small 
Centimeter,  avoiding  any  unnecessary  surplus. 

While  many  varieties  of  dentimeters  have  been  suggested,  a  small 
jeweler's  slide  pin-vise  affords  the  quickest,  easiest  and  most  secure  ad- 
justment, with  less  danger  of  cutting  the  wire  when  twisting. 

The  loop  of  wire  should  be  then  placed  over  the  root,  passed  just 
freely  beneath  the  gingival  border  of  the  gum,  and  twisted  taut,  being 
careful  in  the  meantime  to  conform  and  adapt  it  to  all  concavities  of  the 
root.     Fig.  58. 

In  very  short  roots,  it  may  become  necessary  to  hold  it  under  the 
gum  with  a  suitable  instrument,  to  prevent  displacement  while  twisting; 
and,  while  it  is  usually  most  convenient  to  have  the  twist  upon  the  buccal 


Fiq,60, 


or  labial  surfaces,  in  second  and  third  molars  it  may  sometimes  be  found 
more  convenient  to  twist  from  the  lingual  surface. 

After  securing  the  correct  measurement  of  the  diameter  of  the  root 
the  wire  should  be  cut  in  two  at  a  point  farthest  away  from  the  twisted 
portions,  and  each  end  of  the  former  loop  then  carefully  straightened  out 
until  smooth,  continuous  with  one  another,  and  at  right  angles  with  the 
dentimeter.     Fig.  59. 

When  two  or  more  crowns  are  being  constructed  for  the  same  mouth 
at  the  same  time,  especially  when  the  roots  are  nearly  of  a  size,  each 
measurement  should  possess  some  characteristic  to  distinguish  it  from  the 
other,  by  which  means  any  confusion  in  the  subsequent  fitting  of  the 
band  may  be  avoided.  This  may  be  easily  accomplished  by  so  bending  or 
shaping  the  surplus  ends  as  to  differentiate  between  them,  and  have  each 
designate  the  root  which  it  represents. 


79 


Bands. 


As  the  strength  possessed  by  the  crown,  in  its 
attachment  to  the  root,  increases  in  proportion  to  the 
thickness  of  the  gold  of  which  the  band  is  made,  so 
long  as  it  is  not  too  heavy  to  be  easily  manipulated  and  accurately  adapted, 
and  as  gold  stretches  easily,  and  its  thickness  is  necessarily  diminished  by 
the  subsequent  process  of  finishing  and  polishing,  28  gauge  (B.  &  S.) 
plate,  about  22  karat  in  fineness,  should  be  used  for  bands.  A  gold  for 
this  purpose  is  especially  prepared  by  the  Consolidated  Dental  Alfg.  Co. 
which  is  alloyed  slightly  with  platinum,  and  possesses  the  advantages  of 
strength  and  toughness  as  well  as  being  non-oxidizable,  by  which  name  it 
is  designated. 

The  desired  width  of  the  band  should  be  noted 
with  the  eye,  or,  if  necessary,  measured  with  a  piece 
of  cardboard  trimmed  to  the  correct  width,  or  with  a 
small  compass.     Fig.  60. 

In  cutting  the  gold  the  cervical  edge,  or  that 
which  is  to  be  fitted  to  the  root,  should  be  the  exact 
length  of  the  measurement  ware ;  but  the  variation  or 


mm. 


Eengtl). 


Ficj.BL 


Flq.  62. 


inequality  between  the  diameter  of  the  root,  in  proportion  to  the  dimen- 
sions of  the  space  to  be  filled  by  the  crown,  to  obtain  the  most  artistic  re- 
sults, often  requires  that  one  end  of  the  band  be  cut  on  such  an  angle  as  to 
make  a  difiference  between  the  circumference  of  its  cervical  and  occlusal 
edges  when  soldered.     Fig.  61. 

While  perfectly  straight  edges  will  often  afford  sufficient  opportunity 
for  the  necessary  shaping  and  contouring  of  the  occlusal  end,  it  is  fre- 
quently desirable  and  sometimes  necessary  to  have  this  edge  of  slightly 
larger  proportions,  especially  in  bicuspids,  in  order  to  more  perfectly  and 
artistically  meet  the  requirements  of  contact  and  alignment. 

Where  the  root  is  proportionately  larger  than  the  space  to  be  filled, 
however,  the  converse  of  the  proposition  may  be  indicated,  in  order  to 
secure  and  preserve  an  alignment  of  the  occlusal  surfaces.     In  such  in- 


8o 

stances  the  edges  should  be  cut  straight,  in  order  to  facilitate  the  adapta- 
tion to  the  root,  after  which  the  circumference  of  the  occlusal  edge  may 
be  adequately  reduced. 

When  the  band  has  been  properly  cut  it  should 
SOldcrinS*  be  annealed,  the  edges  filed  smooth,  so  as  to  approxi- 

mate evenly  when  brought  into  contact,  and  then 
-given  circular  form.  Perfect  contact  of  the  edges  is  essential  to  insure  fit 
and  facilitate  soldering,  and  may  be  sustained  by  first  overlapping  and 
then  bringing  them  back  into  direct  contact.  (Fig.  62.)  This  procedure 
condenses  the  molecules  sufficiently  to  overcome  the  expansion,  when 
Jieated,  that  would  otherwise  cause  a  separation,  and  is  preferable  to  wir- 


ing the  outside  circumference  of  the  band 
because  the  solder  not  infrequently  pene- 
trates the  joint  and  attaches  the  wire  to  the 
gold,  which  necessitates  its  being  ground 
off  afterwards. 

When  the  edges  have  been  thus  approxi- 
mated, the  band  should  be  grasped  with 
fine-pointed  pliers  at  a  point  as  remote 
from  the  joint  as  possible,  so  that  they  may 
absorb  but  little  heat.  (Fig.  63.)  Flux 
should  be  applied,  carried  to  the  flame  and 
fused,  and  a  very  small  piece  of  solder  then 
fluxed  and  placed  immediately  over  the 
joint. 

In  soldering,  it  should  be  held  in  the 
flame  so  that  each  edge  will  be  uniformly 
heated,  because  if  either  should  receive  a  preponderance  of  heat 
the  solder  would  become  attached  to  it,  and  the  addition  of  a  second 
rp'iece  may  be  necessary.  Any  more  solder  than  is  required  to  make  the 
joint  is  objectional  because  of  the  additional  stift'ness  imparted  to  the 
band. 

As  it  is  desirable  to  begin  with  a  high  grade  of  solder  to  prevent  sub- 
sequent re-fusing,  and  to  admit  of  finishing  with  as  high  a  karat  as  pos- 
sible, all  bands  should  usually  be  united  with  22  karat  solder,  though 
20  karat  will  answer  the  purpose. 


.63 


8] 


For  convenience  and  comfort,  the  pliers  used  to  hold  the  work  in  the 
flame  should  possess  a  long  handle  and  thin  tapering  points.  (Fig.  64.) 
The  addition  of  platinum  points,  which  may  be  easily  attached  with  any 
hard  solder,  increases  their  usefulness,  as  such  pliers  absorb  less  heat, 
retain  their  shape  more  permanently,  and  offer  more  re- 
sistance to  the  attachment  of  solder. 

The   fitting   of   the   band   may   be 
Titting.  made  accurate,  easy  and  devoid  of  dis- 

comfiture, in  proportion  to  the  relation 
it  bears  to  the  shape  of  the  root  and  to  the  outline  of  its  sur- 
rounding tissue,  before  any  attempt  is  made  to  adjust  it. 
The  detail  of  requirements  in  this  connection  apply  to  any 
style  of  crown  with  a  band,  and  are. 

First — To  conform  the  band  to  the  general  shape  and 
outline  of  the  root. 

Second — To  trim  the  edge  which  is  to  pass  beneath  the 
tissue  to  closely  follozv  the  cervical  curvature  of  the  process, 
and  gingival  festoon  of  the  gum,  so  that  it  will  come  in  con- 
tact ez'enly  and  uniformly  at  all  points,  before  the  final 
necessary  pressure  is  applied. 

Third — To  round  and  smooth  the  edge  so  that  no  irri- 
tating influence  will  be  offered  in  forcing  it  beneath  the  gum. 

I'ourth — For  the  purpose  of  convenience  and  of  avoid- 
ing any  confusion  in  adjusting  and  readjusting;  because  the 
usual  convexity  of  roots  at  this  point  facilitates  the  adapta- 
tion of  the  stiffened  portion  of  the  band,  and  because  of 
placing  the  soldered  joint  where  it  will  be  least  conspicuous 
in  case  of  subsequent  discoloration,  as  well  as  being  most 
easily  accessible  for  reinforcement  in  the  assemblage  of 
bridgework,  the  joint  in  the  band  should  al-jcays  be  placed 
at  the  center  of  the  lingual  surface  of  the  root. 

A  neglect  of  any  of  these  most  essential  features  adds 
materially  to  the  difficulties  experienced  in,  and  the  possible 
discomfitures  resultant  frorn,  the  operation.  In  observing 
them  the  band  should  be  gently  placed  over  the  projecting 
end  of  the  root,  and  shaped  with  pliers  until  it  is  made  to 
conform  to  its  general  outline,  and  any  existing  concavities 
or  inequalities.  Its  surfaces  should  be  made  perpendicular, 
and  the  edge  then  carefully  trimmed  with  curved  pointed 
shears  until  it  meets  the  gum  line  evenly  at  all  points ;  and 
then  nicely  rounded  from  the  outer  surface  with  a  fine  half- 
round  file,  until  blunt  but  smooth.     This  minimizes  the  pos- 


Efg.e4- 


82 

sibilities  of  irritation,  without  obtaining  any  apreciable  thinness  of 
the  gold  which  would  be  objectionable  because  of  increasing  the 
liabilities  of  stretching  and  irritation. 

When  these  requirements  have  been  complied  with,  the  band  should 
be  placed  upon  the  root,  and  gently  pressed  to  place  until  the  edge  passes 
just  freely  beneath  the  tissue.  For  this  purpose  a  small  piece  of  wood  of 
convenient  size,  with  f^at,  smooth  surfaces,  is  most  useful ;  and  if  properly 
used  greatly  facilitates  the  operation,  and  obviates  the  driving  of  a  band 
into  place,  which  is  entirely  unnecessary,  and  even  brutal. 

In  instances  where  a  recession  of  the  gingival  border  of  the  gum  may 
have  exposed  the  root  beyond  the  normal  outline  at  some  point,  such  as  h 
not  infrequently  found  to  present  in  the  mesio-buccal  and  lingual  roots  of 
upper  molars,  an  extension  to  the  band  may  be  indicated  in  preference  to 
sacrificing  it  upon  other  surfaces  sufficiently  to  admit  of  thus  approaching 
the  gum  at  this  point.     This  may  be  best  accomplished  by  first  fitting  the 


band  accurately  without  regard  to  this  extension,  after  which  a  small 
piece  of  pure  gold  plate  may  be  soldered  to  the  outer  surface  of  the  band, 
and  then  trimmed  until  this  denuded  portion  of  the  root  is  covered.  When 
the  necessary  burnishing  has  been  completed,  the  adaptation  may  be  sus- 
tained by  re-enforcing  the  extension  with  a  high  grade  of  solder. 

When  the  cervical  adaptation  has  been  completed,  the  occlusal  edge 
should  be  trimmed  to  afford  accommodation  for  the  adjustment  of  a  cusp 
of  uniform  and  sufficient  depth,  and  then  filed  smooth  and  contoured. 

The  entire  artistic  effect  of  the  finished  crown, 

0ontourin9«  as  well  as  the  prerequisites  of  contact  and  alignment, 

depends  in  a  great  measure  upon  the  form  and  shape 
given  to  the  occlusal  end  of  the  band,  which  can  be  best  observed  at  this 
time. 

By  contouring  is  meant  the  reproduction  of  the  natural  form  and 
outline  of  the  tooth,  and  while  this  may  be  accomplished  with  solder. 


83 

after  the  cusps  have  been  united,  much  time,  energy  and  m.aterial  can  be 
saved,  and  far  more  artistic  results  obtained,  by  properly  shaping  the 
band  itself. 

Artistic  results  in  this  connection,  however,  arc  made  possiljle  only 
by  a  thorough  knowledge  of  the  angles,  characteristics  and  general  forms 
of  the  natural  teeth,  the  outlines  of  which  should  be  reproduced  in  this 
edge  of  the  band.  This  may  be  done  irrespective  of  the  necessary  shape  of 
the  cervical  edge  in  its  adaptation  to  the  root,  and  without  change  of  it. 


Fiq,6G. 


For  contouring  purposes  various  styles  and  designs  of  pliers  are 
used,  but  as  the  shaping  should  be  done  upon  the  edge  of  the  band,  before 
the  cusp  is  attached,  all  of  the  necessary  and  artistic  results  may  be  easily 
accomplished  with  pliers,  the  beaks  of  which  are  straight,  tapering,  and 
come  closely  together,  with  rounded  edges.  A  design  of  the  author's  for 
this  purpose  and  for  universal  use  in  crown  work  is  illustrated  in  Fig.  65, 
and,  while  some  of  the  numerous  other  designs  may  be  found  occasionally 
useful,  these   will  meet  the  general   requirements,   when  properly  used. 


84 

The  rounded  edges  and  one  smooth  beak  prevent  defacing  the  gold,  while 
the  flat  surfaces  and  one  serrated  beak,  and  the  tapering  form  for  stretch- 
ing, adds  to  their  general  usefulness. 

The  average  and  typical  requirements,  and  the  results  possible  from 
a  knowledge  of  the  form  and  outline  of  the  teeth,  and  a  skilful  manipula- 
tion of  the  pliers,  are  indicated  before  and  after  contouring  the  band  in 
Fig.  66. 

In  instances  where  the  diameter  of  the  root  after  its  preparation  is 
larger  than  the  proportionate  dimensions  of  the  occlusal  surface,  to  se- 
cure a  symmetrical  alignment  with  the  adjacent  teeth  it  may  become 
necessary  to  reduce  the  circumference  of  the  occlusal  edge  of  the  band. 
This  may  be  quite  easily  accomplished  by  cutting  numerous  slits  around 
the  approximal  and  lingual  surfaces  of  the  occlusal  edge,  and  then  draw- 
ing the  points  in  and  overlapping  them  until  the  circumference  is  suffi- 
ciently reduced.      (Fig.  67.)     These  places  may  be  afterwards  filled  in 


nq.67. 


with  solder  until  a  smooth  uninterrupted  surface  presents.  Although  the 
pliers  previously  mentioned  may  be  used  successfully,  a  very  convenient 
form  especially  adapted  to  this  purpose,  and  generally  useful  in  reducing 
the  size  of  either  end  of  the  band,  when  occasion  requires,  is  illustrated 
in  Fig.  68. 

After  securing  the  proper  and  desired  contour,  this  edge  should  be 
filed  smooth  and  even,  the  band  then  finally  adjusted  to  the  root,  and 
the  occluding  bite  and  impression  taken. 

The  interior  of  the  band  should  be  filled  even 

OcciUditlS  Bite.        with    the    edge    with    wax    previous    to    taking   the 
occluding  bite.     This  facilitates  the  removal  of  the 
latter  from  the  mouth  and  its  final  adjustment  to  the  model. 

The  occluding  bite  should  always  be  taken  separately  from  the  im- 
pression, and  should  precede  it,  because  the  imprint  of  the  band  is  neces- 
sary to  admit  of  its  adjustment  to  the  model  with  the  band  in  place.   Wax 


85 

is  preferable  for  this  purpose,  because  of  the  ease  with  which  the  relation 
and  a  good  imprint  of  the  teeth  may  be  secured,  and  of  its  more  easy  and 
accurate  adjustment  to  the  model. 

In  obtaining  it  enough  wax  should  be  used  to  secure  the  imprint  of  at 
least  two  teeth  on  each  side  of  the  crown,  whenever  possible,  and  in  the 
procedure  it  should  be  definitely  ascertained  that  the  teeth  are  in  direct 
and  proper  occlusion. 

The  patient  should  then  be  instructed  to  firmly  close  the  jaw, 
and  press  the  wax  against  the  lingual  surfaces  of  the  teeth  with  the 
tongue,  when  by  compressing  it  closely  to  the  buccal  surfaces  with  the 
fingers  a  correct  and  well-defined  bite  is  readily  obtained. 

The    impression    should   alzi'ays   be   taken   with 

Impression.  plaster,  and,  corresponding  with  the  bite,  should  in- 

clude two  or  more  adjacent  teeth,  when  present,  on 
each  side  of  the  crown.     This  is  necessary  in  order  to  prove  and  govern 


7.  €8. 


the  occlusion  when  mounted  upon  the  articulator.  The  use  of  plaster  is- 
essential^  for  this  purpose,  because  of  the  difficulty  of,  and  uncertainty  in, 
readjusting  the  band  to  its  accurate  position  in  the  impression,  when  any 
m.aterial  is  used  which  draws  perceptibly  in  removing  from  the  mouth.. 
This  may  be  done  with  a  degree  of  absolute  certainty  when  plaster 
is  used. 

Partial  impression  trays  of  convenient  size  for  this  purpose  are  iMus- 
trated  in  Fig.  69,  two  being  adapted  for  the  right  an^  left  sides,  and 
one  for  universal  use ;  the  latter,  of  course,  is  the  most  generally'  use- 
ful. Because  of  the  natural  shape  of  the  teeth,  it  will  usuallv  be  found 
necessary  to  break  the  impression  in  removing  it  from  the  mouth,  which 
is  not  objectionable  if  the  parts  are  afterward  accurately  replaced.     A 


convenient  tray,  recently  designed  by  Dr.  E.  L.  Townsend  to  facilitate 
such- procedure,  includes  a  separable  base  composed  of  two  smaller  trays 
with  the  dividing  line  in  the  center.  Upon  the  removal  of  the  outer  tray 
these  remain  in  place,  when  they  may  be  easily  divided  by  the  insertion  of 


the  blade  of  a  small  penknife,  which  separates  the  impression  in  two  lateral 
halves.     (Fig.  70. ) 

When  the  parts  are  accurately  readjusted  and  their  relation  securely 
sustained  with  melted  wax,  the  impression  should  be  then  varnished,  filled, 
separated,  the  bite  adjusted,  and  then  mounted  securely  upon  the  ar- 
ticulator.    For  the  purpose  of  facilitating  the  separation  of  the  modc-1 


87 

from    the    impression,    the    latter 
should  be  first  coated  with  a  thin 
solution  of  shellac  in  alcohol,  and 
followed,  after  drying,  with  a  coat- 
ing of  very  thin  sandarac,  in  alco- 
hol.    The  former  causes  a  line  of 
demarcation  of  inestimable  value  in 
separating,  and  the  latter  gives  a 
smooth,  hard  surface  to  the  model. 
Because     of 
Jlrtkulators.         the  desirability 
of  obtaining  a 
degree  of  accuracy   in   articulation 
as  well  as  occlusion,  a  reproduction 
of  the  lateral  movements  of  the  jaw, 
such  as  are  made  possible  by  the  use 
of  an  anatomical  articulator,  is  al- 
most as  essential  in  crown  work 
as  it  is  in  the  construction  of  ar- 
tificial dentures. 
For  single  crowns,  however,  such  requirements,  while  always  desir- 
able  are  not  so  essentially  necessary,  and  in  the  absence  of  a  design  more 
con;eniently  adequate  for  the  purpose,  the  ordinary  crown  articula- 
tor  may  answer.      (Fig.  71.) 


r/q.  70. 


Fij.  71. 

Procmcs  for  €ttsp  Tormation. 


Of  the  various  methods  and  systems  for  securing  suitable  cusp  forms 
that  will  typify  the  natural  teeth,  and  meet  the  requirements  of  articula- 


tion  and  occlusion,  but   one  general   line  of  procedure  offers   absolute 
certainty  and  accuracy  in  all  cases. 

The  importance  of  true  occlusion,  as  has  been  previously  empha- 
sized, will  be  readily  apparent,  and  is  generally  conceded,  and  yet  through- 
out the  entire  evolution  of  methods  for  procuring  it,  a  system  of  stereo- 
typed typical  dies  has  predominated.  As  the  conditions  presenting  vary 
in  proportion  to  the  degree  of  the  normal  accuracy  of  occlusion,  position 
of  the  root,  and  its  relation  to  adjacent  teeth,  and  the  length  and  shape  of 
band  and  depth  of  cusp  required,  the  fallacy  of  expecting  a  ready-made 
form  to  closely  fit  and  approximate  the  edge  of  a  properly  contoured 
band,  and  then  articulate  and  occlude  accurately  with  the  opposing  teeth, 
is  manifest. 

Carved  Cusp  and  Special  Die  methods. 

If  these  mechanical  and  artistic  requirements  are  to  be  observed,  the 
prerequisites  of  certainty  and  accuracy  can  be  best  obtained  by  forming 


the  cusp  directly  from  an  imprint  of  the  opposing  teeth,  and  in  its  proper 
relation  to  the  band,  as  was  originally  suggested  in  primitive  form  by  Dr. 
Norman  W.  Kingsley.  While  the  detail  of  such  a  procedure  may  probably 
consume  a  little  more  time  than  some  methods,  time  is  not  the  only  factor 
to  be  considered,  except  perhaps  by  dental  laboratories;  and  the  results 
will  usually  justify  such  an  expenditure. 

When  the  models  have  been  securely  mounted 
Procedure  upon  the  articulator  (Fig.  72),  all  surfaces  of  the 

plaster  in  close  proximity  to  the  band  should  be  var- 
nished with  a  thin  coating  of  collodion,  sandarac  or  silex.     The  band 


89 


rihould  now  be  filled  with  thin,  well  mixed  plaster,  into  which  the  occusal 
surfaces  of  the  opposing  teeth  are  then  imprinted  by  firmly  closing  the 
articulator.  (Fig.  y2>-)  The  reproduction  of  adjacent  teeth  in  the  model 
serves  to  sustain  and  prove  the  proper  occlusion.  When  this  has  become 
sufficiently  crystallized,  the  articulator  should  be  opened,  and  the  band, 
with  its  plaster  contents,  detached  from  the  model  in  such  manner  as  to 
preserve  its  definite  outline  and  relation.     The  surplus  plaster  around  the 


F/<f.  73. 

outer  edge  of  the  band  should  be  removed  with  the  sharp  blade  of  a 
small  penknife,  which  leaves  the  remaining  contents  somewhat  crude  and 
inartistic  in  outline,  but  accurate  in  occlusion.  (Fig.  74.)  An  artistic 
effect,  in  proportion  to  the  degree  of  skill  possessed  by  the  operator,  may 
be   obtained,  by   inserting  the   grooves   and  pits   of   the    typical   outline 


^y.  74. 


Fiq.  75. 


of  the  tooth,  which  may  be  done  without  perceptible  change  to  the  occlu- 
sion. In  fact,  the  latter  is  thus  improved  because  of  the  formation  and 
separation  of  the  cusps.      (Fig.  75.) 

While  modeling  compound,  mouldine  and  wax  are  sometimes  em- 
ployed for  the  formation  of  cusps,  the  use  of  any  of  them  is  not  so  reliable 
as  plaster,  because  of  the  tendency  to  flake  in  carving,  or  of  the  suscer^ti- 
bility  to  change  form  in  the  subsequent  process  of  securing  the  mould  for 


90 

the  die,  or  for  casting.  In  the  process  of  carving,  it  is  not  ahogether 
necessary  that  the  correct  anatomical  outhne  of  the  tooth  should  be  repro- 
duced, but  only  to  typify  it  sufficiently  to  designate  the  tooth  it  represents. 
This  may  be  easily  accomplished  by  inserting  the  grooves  deep  enough  to 
separate  the  cusps,  and  typical  enough  in  outline  to  distinguish  the  right 
from  the  left,  and  the  upper  from  the  lozvcr.     (Fig.  76.) 

In  the  reproduction  of  the  plaster  cusp  in  gold,  two  methods  of  pro- 
cedure are  employed,  by  means  of  which  plate  gold  may  be  conformed  by 
swaging  between  dies,  or  a  solid  cusp  produced  by  casting. 

Because  of  the  possibilities  for  securing  a  more 

Swaged  €USPS.         distinct  and  definite  reproduction  of  the  outline;  of 

the  time  saved  in  adjusting  and  adapting  the  cusp  to 

the  band,  and  of  securing  adequate  thickness  of  cusp  by  subsequent  re- 


III!  j|  ipkii 


RIGHT  LEFT  rvlCHT 

F/a.76. 


LEFT 


7 


enforcement  with  solder,  the  swaged  method  is  usually  preferable. 
For  this  procedure  the  plaster  cusp  should  be  trimmed  away  uniformly 
around  its  peripheral  border,  until  the  edge  of  the  band  is  exposed.  This 
reduction  in  size  allows  for  the  thickness  of  gold  forming  the  cusp,  and 
renders  possible  a  perfect  approximation  of  the  edges  of  cusp  and  band. 
If  not  observed,  the  cusp  will  be  as  much  larger  than  the  band  as  its 
thickness,  which  will  require  the  use  of  solder  in  securing  a  smooth  sur- 
face in  its  subsequent  attachment. 

A   moulding    ring    (Fig.  yy)    should   be    filled 
mould.  even  and  flush  to  its  edges  with  mouldine,  into  the 

center  of  one  surface  of  which  the  plaster  cusp,  after 
being  dusted  with  lycopodium  or  soapstone,  should  be  firmly  imprinteJ 
just  deep  enough  to  secure  the  outline  of  the  exposed  edge  of  the  band. 
The  mouldine  should  be  packed  closely  against  the  band  around  its 
circumference,    and    the    band    and    plaster    cusp    removed    from    the 


mould.    This  should   be  dusted   with  lycopodium   and  the  dies   secured. 

The  most  useful  and  coixvenient  system  of  dies 

Dk$.  may  be  secured  by  placing  a  casting  cup  (Fig.  78), 

which  has  a  small  perforation  through  the  center  of 

the  base,  over  the  mould,  and  casting  a  cusp-button  of  pure  tin  or  Watt's 

metal  (Fig.  79).     After  cooling,  the  button  should  be  detached  from  the 

cup  with  a  small  knife-blade,  and  placed  upon  a  smooth  surface  of  mould- 


/"/c?.77. 


f/g.  80. 


Fftj.ai. 


FiQ.82. 


me,  in  the  moulding  ring,  then  dusted  freely  with  lycopodium,  and  the 
rubber  ring  adjusted  for  the  purpose  of  securing  the  counter-die  (Fig.  80), 
which  is  poured  with  fusible  alloy. 

A  higher  fusing  metal  than  any  of  the  fusible  alloys  is  necessary  for 
casting  the  cusp-button  m  order  to  preclude  the  probability  of  melting  it 
in  securing  the  counter-die. 


92 

In  the  process  of  forming  the  cusp  with  these  dies  (Fig.  8i),  the 
swaging  should  be  done  in  the  counter-die  by  the  use  of  an  ingot  of  lead, 
or  a  large  buckshot,  until  closely  adapted,  after  which  the  surplus  gold 
should  be  cut  away  and  the  cusp-button  used  for  the  final  sv/aging  only,  to 
bring  out  the  finer  lines.  These  cusp-buttons  may  be  preserved  and  found 
useful  wherever  occasion  admits  of  the  use  of  ordinary  and  typical  dies, 
such,  for  instance,  as  the  absence  of  occluding  and  adjacent  teeth. 

Another  method  somewhat  more  simple  is  to  secure  the  mould  as 
indicated,  and  then  adjust  the  rubber  ring  and  pour  the  die  of  fusible 
alloy.  The  surface  is  then  dusted  with  lycopodium  or  coated  with  a  solu- 
tion of  whiting  in  alcohol,  the  rubber  ring  readjusted,  and  a  counter-die 
of  the  same  metal  and  dimensions  secured.     (Fig.  82.) 

While  this  will  answer  the  purpose,  if  the  swaging  is  done  in  similar 
manner,  the  tendency  of  stretching  and  probability  of  tearing  the  gold 


will  be  increased,  especially  if  the  cusp  is  very  deep,  because  of  the  diffi- 
culty of  swaging  and  conforming  gold,  or  any  metal,  to  any  given  or  de- 
sired shape  between  two  surfaces  of  like  and  equal  resistance,  in  which, 
respect  lies  the  advantage  of  the  former  method. 

In  the  process  of  swaging,  the  surfaces  of  the  dies 
Swagiltd,  should  be  oiled  to  facilitate  the  procedure,  and  pre- 

vent sticking.  A  convenient  method  of  preventing 
the  defacing  of  the  gold  is  to  stretch  a  piece  of  rubber  dam  over  it  before 
driving  into  the  counter  die.  This  also  avoids  any  coating  of  the  die  metal 
from  adhering  to  the  surface  o^  the  gold.  The  chances  of  tearing  the  gold 
may  be  reduced  to  a  minimum  by  first  swaging  a  few  layers  of  heavy 
tinfoil  covered  by  the  rubber  dam.  This  slightly  compresses  the  metals 
and  affords  space  for  the  gold  between  the  two  surfaces  of  the  dies, 
and  it  should  first  be  carefully  worked  down  into  the  counter  die  with 


93 


a  small  blunt-pointed  piece  of  wood.  The  gold 
used  should  be  of  the  same  karat  and  color  as  the 
band,  and  of  28  gauge  thickness,  as  it  is  to  be 
subjected  to  considerable  stretching.  It  should 
be  cut  somewhat  larger  than  the  diameter  of  the 
cusp  to  be  formed,  and  frequently  annealed  dur- 
ing the  process ;  and  a  round  or  disk-shaped  piece 
of  plate  will  yield  more  readily  to  the  desired 
conformation  between  the  dies,  with,  less  ten- 
dency to  overlap  at  the  angles;  and  all  unneces- 
sary surplus  should  be  removed  before  the  final 
swaging.  Steady  and  uniform  pressure,  such  as 
would  result  from  the  use  of  a  press  of  adequate 
power,  would  be  productive  of  better  results,  in 
the  absence  of  which  a  heavy  hammer  and  direct 
blow  will  answer. 

When  the  swaging  has 
Jfdjusiing  Cusp.  been  completed,  the  edge  of 
cusp  should  be  carefully 
trimmed  down  to  the  line  marking  its  point  of 
contact  with  the  band,  which  should  be  outlined 
in  the  gold.  This  point  can  be  approached  with 
small  curved  crown  shears,  but  the  final  trimming 
should  be  done  with  a  fine  flat-surface  gold  file, 
and  may  be  best  and  more  uniformly  accom- 
plished by  holding  the  file  steady  and  carrying 
the  cusp  backward  and  forward  over  its  surface. 
The  plaster  cusp  should  then  be  removed  from 
the  band,  and  the  latter  adjusted  to  place  on  the 
articulator.  After  filling  the  interior  of  the  band 
with  wax  to  sustain  the  cusp,  it  should  be  con- 
secutively trimmed  and  tried  to  place  until  the 
edges  approximate  evenly,  and  the  desired 
occlusion  is  obtained  and  proven  by  the  firm 
closure  of  the  articulator.     (Fig.  83.) 

The  necessary  re-en- 
Somerlltfl  Cusp.  forcement  of  the  cusp  to 
fortify  it  against  constant 
and  continued  attrition  may  be  done  with 
solder  simultaneously  wath  its  attachment  to 
the  band,  although  no  objection  is  offered  to 
filling   the    cusp    with    solder    previous    to    its 


■ 


94  ■ 

subsequent  attachment  if  done  with  the  same  karat  that  would  be 
indicated  and  used  in  the  joint.  During"  the  process  of  solder- 
ing, the  relation  between  cusp  and  band  should  be  securely  sus- 
tained. This  can  be  best  accomplished  by  the  use  of  automatic  pliers  de- 
signed for  the  purpose  as  indicated  in  Fig.  84,  the  use  of  wire  being  objec- 
tionable for  the  same  reasons  previously  mentioned  in  connection  with 
soldering  the  band. 

The  parts  should  be  treated  to  the  acid  bath,  freely  washed  with  water, 
and  adjusted  in  the  pliers.  Flux  should  then  be  applied  to  the  joint  and 
fused,  and  the  parts  united  with  22  or  20  karat  solder.  The  necessary 
re-enforcement  may  be  obtained  with  18  karat  solder.  In  case  of  a 
perforation  of  the  gold  as  a  result  of  swaging,  the  same  should  be  first 


Fi<j.85, 


filled  with  foil,  when  no  trouble  will  be  experienced  in  covering  it  over 
or  filling  it  in  with  solder. 

When    the    soldering   has    been    completed,    the 

Tinisbins.  crown  should  be  again  treated  to  the  acid  bath  to 

dissolve  remaining  borax,  then  dressed  down  with 

carborundum  stones  and  disks  in  the  engine,  and  finally  polished  on  the 

lathe. 

While  no  special  or  particular  advantage  is  af- 
Solid  Cast  €u$D$.  forded  by  the  formation  of  a  solid  or  cast  cusp, 
excepting  that  the  presentation  of  a  faulty  or  inaccu- 
rate occlusion  may  be  remedied  by  grinding  freely  without  exposing  the 
solder,  yet  many  prefer  to  pursue  this  method.  When  such  procedure 
seems  desirable,  the  plaster  cusp,  after  carving,  should  be  left  Hush  and 
continuous  with  the  outside  edge  of  the  band. 

The  moulding  ring  should  be  filled  with  mouldine,  and  the  mould  of 
the  cusp  secured  on  a  line  with  the  edge  of  the  band.     This  should  then 


95 

be  placed  over  the  Bunsen  burner  and  allowed  to  remain  until  the  mould- 
ine  becomes  hard.  Asbestos  of  adequate  thickness  to  accommodate  the 
depth  of  the  cusp  may  also  be  used  for  the  mould  by  saturating  it  with 
water  until  a  suitable  imprint  of  the  plaster  cusp  can  be  made  in  it,  after 
which  it  should  be  dried  in  the  same  manner.  Scrap  gold  of  sufficient 
quantity,  sparingly  fiuxed,  should  be  fused  in  the  mould,  and,  when 
molten,  may  be  easily  cast  by  quickly  pressing  it  into  the  matrix  with  a 
smooth  surface  of  carbon  or  steel  large  enough  to  cover  the  entire  area  of 
the  cusp.  (Fig.  85.)  The  principal  objection  offered  to  this  method  is 
the  time  ordinarily  required  to  trim  and  file  the  surface  until  a  perfect 
approximation  with  the  band,  and  the  necessary  requirements  of  occlu- 
sion are  obtained. 

€u$p  Tormation  without  models. 

The  same  detail  of  procedure  is  applicable  to  the  formation  of  cusps 
without  the  use  of  models  or  articulator.  The  results,  however,  while 
perhaps  occasionally  as  artistic,  are  not  so  accurate,  because  no  guide  for 


obtaining  the  correct  length  of  cusps  is  present,  and  no  opportunity  is 
afforded  for  proving  the  articulation  and  occlusion  in  the  final  adjust- 
ment and  attachment  of  the  cusps  to  the  band,  unless  it  be  done  directly 
in  the  mouth. 

When  the  employment  of  such  a  procedure  may  seem  mdicated,  of 
when  it  may  be  desirable  or  necessary  to  complete  the  crown  at  a  single 
sitting,  the  band  in  position  on  the  root  may  be  filled  with  a  sufficient 
quantity  of  plaster,  in  the  plastic  state,  or  with  modeling  compound,  and 
the  teeth  closed  directly  into  it.  After  thoroughly  hardening  it  should  be 
removed,  the  surplus  trimmed  away  even  with  the  band,  and  the  desired 
and  typical  shape  and  form  then  given  it  by  carving,  as  is  consecutively 
illustrated  in  Fig.  86,  when  the  dies  or  mould  may  be  obtained  in  the 
manner  outlined,  and  the  crown  finished,  as  indicated. 

Jlsb's  Crown  Swaging  Dei^ice. 

Ash's  crown  swaging  device,  which  consists  of  a  cylinder  and 
plunger,  and  a  soft  rubber  or  hydraulic  pad,  will  be  found  quite  useful 


96 

for  swaged  cusps,  because  of  eliminating  the  necessity  for  the  use  of  any 
counter-die,  or  of  swaging  between  two  surfaces  of  metal,  and,  by  pre- 
venting any  rebound,  displacement  or  defacing  of  the  gold  during  the 
process.  , 

In  its  use  the  mould  from  which  the  die  is  secured  must  be  obtained 
in  a  moulding  ring  of  suitable  dimensions,  to  render  it  of  a  size  corre- 
sponding to  the  interior  diameter  of  the  cylinder.  These  are  included  in 
an  outfit  suggested  by  Dr.  E.  G.  Christiansen,  of  Dremmen,  Norway, 
and  manufactured  by  C.  Ash  &  Sons. 


Ficj.QT, 


When  the  die  has  been  secured  with  fusible  alloy  it  should  be  placed 
in  the  cylinder,  the  gold  annealed  and  placed  in  position,  and  the  soft 
rubber  or  hydraulic  pad  then  inserted. 

The  plunger  is  then  adjusted,  and,  upon  being  driven  into  the  cylin- 
der, results  in  the  swaging  being  easily  and  quickly  accomplished,  with- 
out danger  of  tearing  or  defacing  the  gold. 

If  the  cusp-button  method  of  dies  has  been  employed,  and  the  button 
afterward  used  only  to  bring  out  the  finer  and  more  definite  lines,  the 
swaging    may    be    done    in    the    counter    die    in    the    same    manner 

(Fig-  87)- 


97 


Die  and  Die  Plate  Itletboils. 

The  advent  of  the  die  and  the  die-plate  systems  was,  primarily,  the 
outcome  of  a  desire  for  ohtaining  more  natural  and  artistic  results  in  the 
process  of  cusp-formation  than  was  then  possible  by  pursuing  the  primitive 
method.  Originally,  efiforts  in  this  line  were  confined  to  soldering  a  flat 
surface  of  gold  to  the  band,  and  then  building  the  cusps  at  various  points 
upon  this  surface  with  small  globules  of  scrap  gold,  or  pieces  of  triangu- 
lar platino-iridium  wire,  attached  with  solder ;  or  with  solder  alone,  and 
subsequently  grinding  to  the  desired  form  and  occlusion. 

While  many  of  these  somewhat  crude,  inaccurate  and  inartistic 
efforts  were  successful  from  the  standpoint  of  serviceabilitv  and  useful- 
ness, the  introduction  of  dies  soon  followed.  These  were  designed  to 
serve  as  a  means  of  securing  more  artistic  results,  and  as  a  time-saving 
procedure. 

The  first  productions  in  this 
Tndit>idual  Dies.  line  were  individual  dies,  ob- 
tained directly  from  the  natural 
teeth.  For  this  purpose  suitable  extracted  teeth  were 
selected,  and  mounted  in  a  base  of  plaster.  This  was 
then  trimmed  to  favorable  shape  for  securing  a  mould 
in  sand,  from  which  a  casting  was  made  of  zinc. 

Plate  gold  was  then  swaged  to  conform  with  tl 
outlines  of  the  natural  cusps  by  driving  the  die  into 
smooth  surface  of  lead,  or  an  old  discarded  counter-di 

This  method  was  productive  of  so  great  a  degre 
of  improvement  over  the  former  procedure  as  to  sut 
sequently    induce   the    supply-houses    to    manufactuit 
these  dies  in  sets  of  various  numbers,  and  made  of 
brass  in  order  to  be  more  permanent  and  indestructible 
(Fig.  88). 

Because  of  the  immediate  necessity  for  a  suita- 

Dle-PlafC$.  ble  counter-die,  and  of  the  advantage  of  combining 

a  larger  variety  of  cusp-forms  into  more  convenient 

and    compact    order,    the   introduction    of   the    die-plate    was    a    natural 

sequence. 

These  comprise  various  numbers  of  cusp-moulds  in  a  brass  or  steel 
castmg.  In  their  use  the  swaging  is  easily  and  quickly  accomplished  by 
driving  the  disk  of  gold  into  the  mould  selected  to  best  approach  the  re- 
quirements, with  an  ingot  of  lead  or  alloy  of  lead  and  tin.  Ingots  for  the 
purpose  may  be  previously  cast  in  any  quantity,  and  of  adequate  and  con- 
venient sizes  by  the  use  of  a  hub-mould  designed  for,  and  usually  accom- 
panying, the  die-plate  (Fig.  89).     Ordinary  buckshot,  however,  are  easy 


Fi 


'1 


98 


to  procure,  and,  if  of  suitable  size,  will  answer  the  purpose  nicely.  The 
steel  plates  may  also  be  thus  employed,  or  may  be  used  to  produce  solid 
cusps  by  driving  an  ingot  of  scrap  gold  into  the  mould  selected. 

While  these  plates  are  still  in  common  use  their  value  and  range 
of  application  increases  in  proportion  to  the  number  and  variety  of  cusp- 
forms  contained,  and  their  limitations,  of  course,  decrease  in  inverse 
ratio. 

In  their  use  the  mould  should  be  selected  which 

Jlt)p]ication.  best  represents  the  individual  tooth  to  be  crowned^ 

and  meets  or  approaches  the  size  of  the  band.     The 

requirements  of  occlusion  must  be  secured  in  the  fitting  and  adjustment 

of  the  cusps  to  the  band,  which  can  only  be  observed,  of  course,  after 

swaging  the  cusps. 

With  cusps  formed  by  any  die-plate  system  or 

JldjUStins  method  the  best  and  most  accurate  relation  can  be 

Witl)  models*  secured  with  models  mounted  upon  the  articulator. 

Opportunity  is  thus  afiforded  for  trimming  the  band 


Fi<j.d9. 

or  the  cusps,  until  their  approximation  admits  of  a  favorable  occlusion, 
which  can  be  noted  upon  the  lingual  as  well  as  the  buccal  surfaces. 

More  perfect  occlusion  may  often  be  obtained  by  depressing  the 
cusps  with  a  blunt  instrument,  or  piece  of  wood ;  or,  if  necessary,  by 
building  up,  wherever  indicated,  with  a  high  grade  of  solder.  Small 
globules  of  scrap  gold  or  pieces  of  gold  or  platinum  wire  facilitate  such 
procedure  by  affording  a  guide  as  to  the  desired  formation  and  location, 
and  by  requiring  the  control  of  less  solder  in  their  attachment. 

When  the  requirements  of  occlusion  have  been  thus  observed,  an 
effort  should  be  made  to  closely  approximate  the  edges  of  cusps  and 
band.  This  may  be  done  by  adjusting  the  one  to  the  other  with  pliers,, 
if  care  be  exercised  so  as  not  to  distort  the  shape  of  the  band  and  destroy- 
its  contact  and  alignment.  Any  necessary  filling  in  or  subsequent  con- 
touring may  be  done  with  solder  in  the  final  attachment.  Where  a  con- 
siderable space  exists  between  the  two  portions,  the  process  of  soldering 
is  facilitated  by  burnishing  a  piece  of  thin  pure  gold  plate,  or  packing^ 
foil  gold  into  such  spaces. 


99 

In  emergencies,  or  where  it  may  seem  desirable 
HdjUSdng  to  complete  the  crown  without  models,  and   secure 

Without  models.  the  adjustment  in  the  mouth,  the  fitting  may  be 
facilitated  by  filling  the  interior  of  the  band  with 
wax  to  temporarily  sustain  the  cusps  during  the  process.  When  the 
parts  have  been  approximated,  a  more  perfect  occlusion  may  often  be 
obtained  by  tacking  the  cusps  to  the  band  at  one  point  with  a  very  small 
bit  of  solder,  and  then  replacing  the  crown  and  having  the  opposing 
teeth  closed  firmly  into  it,  after  which  the  soldering  may  be  completed, 
and  the  necessary  reinforcement  given.  If  the  requirements  are  particu- 
larly difficult,  the  process  may  be  further  facilitated  by  swaging  the  cusps 
of  30  gauge  pure  gold.  This  is  so  much  more  yielding  and  will  offer  so 
little  resistance  to  the  closure  of  the  teeth  into  firm  occlusion,  as  to  insure 
moderately  accurate  results,  but  such  cusps  should  be  attached  with  a 
very  high  grade  of  solder,  as  the  extreme  softness  of  the  gold  will  soon 
result  in  its  exposure.  This  procedure  is  equally  applicable,  of  course,  to 
the  adjustment  of  cusps  formed  by  any  system  or  method  employed. 

1)ollin9$wortb  System. 

Ihe  great  variation  in  the  size,  shape  and  depth  of  cusps  necessary 
to  meet  or  approach  the  requirements  of  this  style  of  crown  construction, 
and  the  previous  absence  of  any  system,  or  definite  detail  in  the  work, 
resulted  in  the  introduction  of  the  HoUingsworth  System,  devised  by  Dr. 
J.  G.  HoUingsworth. 

This  was  the  first  system  embracing  a  detailed  line  of  procedure  in 
the  construction  of  gold  crowns,  and  because  of  including  a  large  variety 
and  selection  of  typical  forms,  of  its  simplicity,  and  of  being  so  great  an 
improvement  over  former  methods,  it  is  much  used. 

It  comprises  about  two  hundred  typical  occlusal  forms  in  the  shape 
of  cusp-buttons,  and  a  good  selection  of  moulds  of  the  buccal  surfaces  of 
bicuspids  and  molars,  and  of  the  labial  and  lingual  surfaces  of  the  anterior 
teeth. 

Those  for  the  buccal  surfaces  of  bicuspids  and  molars  are  designed 
for  the  purpose  of  securing  a  more  artistic  shape  in  these  surfaces  of  the 
band  by  swaging,  or  for  gold  reproductions  of  the  entire  tooth.  For  the 
former  purpose,  however,  such  procedure  by  any  system  is  unnecessary, 
because  of  the  time  consumed,  and  of  the  possibilities  for  otherwise,  and 
more  quickly  securing  a  proper  and  equally  artistic  shape.  While  such 
moulds  may  often  be  found  useful  for  obtaining  all  gold  dummies  for 
bridge  construction,  those  for  the  anterior  teeth  are  practically  useless, 
because  of  the  limited  indications  for  the  application  of  such  crowns. 

The  variety,  form  and  convenient  shape  of  the  cusp-buttons,  how- 


lOO 


ever,  affords  for  them  a  more  or  less  extensive  range  of  application  and 
usefulness.  They  are  made  of  a  metal  which  is  moderately  indestructible, 
and  are  used  only  for  the  purpose  of  forming-  the  die  for  the  subsequent 
conformation  of  the  gold  by  swaging,  or  for  securing  the  mould  in  asbes- 
tos for  the  purpose  of  obtaining  solid  cast  cusps,  as  previously  indicated. 

The  convenient  size  of  the  cusp-buttons  possesses  the  advantage  of 
facilitating  the  selection  of  the  one  most  favorable  to  meet  the  require- 
ments, which  may  be  accomplished  by  trying  to  place  upon  the  band,  on 
the  articulator,  or  in  the  mouth. 

Aside  from  the  forms,  the  system  consists  of  a  steel  moulding  plate 
and  suitable  rubber  moulding  rings. 

When  the  cusp-button  which  best  represents  the 

Jlpplication.  tooth,  and  meets  the  requirements  of  occlusion  and 

approximation  with  the  edge  of  band,  has  been 
selected,  it  should  be  deposited  upon  the  moulding  plate,  and  the  rubber 
ring  placed  around  it.  Fusible  alloy  should  be  then  melted  and  poured 
into  the  ring.  In  pouring,  it  should  be  directed  immediately  upon  the 
center  of  the  cusp-button,'*"in  order  to  prevent  an  imperfect  die,  or  one 
not  entirely  surrounded  with  metal. 

When  the  fusible  alloy  has  crystallized,  it  should  be  cooled  by  dip- 
ping into  water,  and  the  rubber  ring  then  detached.  The  cusp-button 
may  be  then  easily  separated  by  gently  tapping,  and  replaced  in  the  tray, 
and  the  die  is  ready  for  the  swaging  of  the  gold.  This  is  accomplished 
in  the  manner  indicated,  by  the  use  of  a  buckshot,  or  ingot  of  lead,  driven 
to  place  with  a  swaging  hammer,  after  which  the  surplus  may  be  trimmed 
away,  and  the  cusps  finally  adjusted  to  proper  relation  with  the  band  and 
occlusion,  and  then  soldered. 

The  use  of  these  cusp-buttons  offers  the  additional  advantage  of 
affording  opportunity  for  modifying  or  improving  the  occlusion  when 
indicated,  by  building  the  cusps  up  with  mouldine  at  the  desired  points, 
and  to  the  desired  depth,  before  pouring  the  die.  Also,  in  cases  where 
the  band  may  be  so  short  as  to  require  a  deeper  cusp,  this  may  l^e  easily 
secured  by  raising  the  cusp-button  on  the  moulding  plate  with  a  base  of 
mouldine  of  sufficient  thickness  to  make  up  the  deficiency  in  depth,  and 
trimmed  to  closely  follow  the  outline,  before  pouring  the  die. 

m\mr%  system. 

One  of  the  most  modern  inventions  in  die-plates,  and  processes  of 
swaging,  and  one  possessing  some  new  and  good  features,  has  been  re- 
cently  introduced   in  Millett's   System. 

This  consists  of  a  large  die-plate  comprising  about  four  hundred 
raised  moulds  of  cusp-forms,  and  buccal  and  labial  surfaces,  sy=<-emati- 


lOI 

cally  arranged  in  sizes,  and  for  each  side  of  the  mouth,  and  the  necessary 
apparatus  for  swaging. 

While  the  forms  are  similar  in  size  and  shape  to  those  of  the  Hol- 
lingsworth  System,  the  die-plate  offers  a  greater  range  of  application  in 
a  larger  variety  for  selection,  and  the  advantage  of  each  one  being  an 
integral  part  of  the  plate,  which  overcomes  the  possibility  of  the  disar- 
rangement or  loss  of  any  of  them. 

This,  together  with  the  method  of  securing  the  die,  and  the  process 
of  swaging,  without  doubt  affords  greater  simplicity  and  quicker  results, 
but  the  important  feature  of  not  being  able  to  adjust  the  cusp-forms  to 
position  on  the  band,  as  an  aid  in  their  proper  selection,  is  a  disadvantage. 

The  apparatus  for  swaging  includes  a  cylinder  and  plunger,  and  a 
bed-plate  and  soft  rubber  block,  which  are  similar  to  Ash's  crown  swag- 
ing outfit. 

The  bed-plate   is   designed   for   the   purpose  of 

Jlpplication.  holding   a    sufficient    quantity    of   ordinary    sealmg- 

wax  to  secure  a  die  of  any  of  the  individual  moulds, 
and  fits  accurately  in  the  cylinder. 

The  sealing-wax  contained  in  the  bed-plate  is  softened  by  passing 
through  a  flame,  and  then  pressed  firmly  over  the  form  selected  to  be 
duplicated  in  gold,  and  which  is  calculated  to  be  the  nearest  approach  to 
the  requirements. 

This  gives  an  accurate  impression  of  the  form,  in  the  wax,  which, 
after  chilling  in  cold  water,  is  sufficiently  hard  to  answer  the  purpose  of 
a  die. 

This  is  placed  in  the  cylinder,  the  gold  annealed  and  placed  on  top 
of  it,  the  soft  rubber  block  inserted,  the  plunger  placed  over  all,  and  the 
swaging  accomplished  by  driving  the  plunger  into  the  cylmder  with  a 
moderately  heavy  swaging  hammer. 

In  cases  where  a  deeper  cusp-form  is  desired,  or  necessary,  a  rim  of 
warm  sealing-wax  may  be  moulded  around  the  edge  of  the  imprint  until 
sufficient  increase  of  depth  is  obtained,  before  swaging.  Where  a  more 
shallow  reproduction  is  indicated,  the  sealing-wax  may  be  trimmed  or 
pared  down  accordingly ;  or,  if  the  summits  of  one  or  more  of  the  indi- 
vidual points  or  cusps  need  to  be  made  more  pronounced,  the  die  may  be 
deepened  at  such  points  with  a  sharp  bur  or  suitably  shaped  cutting  in- 
strument. 

Cowry  System. 

This  system,  devised  by  Dr.  H.  S.  Lowry,  departs  from  other  methods 
where  moulds  are  used,  and,  like  the  original  die-plates,  comprises  the 
actual  dies  to  be  used  in  the  process  of  swaging. 


102 

The  improvement  lies  in  the  more  extensive  selection,  and  the  sup- 
plemental trial  caps  which  represent  the  exact  size  and  formation  of  the 
dies. 

The  dies  are  individual  in  character,  made  of  a  practically  indestruc- 
tible metal,  and  each  one  is  numbered.  The  trial  caps  are  numbered  cor- 
responding with  the  dies  of  which  they  are  counterparts,  and  are  pro- 
vided with  a  projecting  stem,  which  facilities  holding  and  handling 
them  in  their  adjustment  to  the  band,  in  the  process  of  selecting  the  one 
best  suited  to  the  requirements. 

The  system  includes  a  moderately  good  selection  of  about  sixty  dies 
of  cusp-forms ;  and  a  smaller  number  of  the  buccal  surfaces  of  bicuspids 
and  molars,  and  the  labial  surfaces  of  the  anterior  teeth,  with  correspond- 
ing complement  dies,  together  with  a  "stamper"  for  swaging,  and  solder- 
ing pliers  for  general  use. 

The  trial  caps  are  adjusted  to  position  on  the 

JTpplication,  band,  until  a  selection  is  made,  of  the  one  which  best 

meets  the  requirements.  The  number  of  this  is 
noted,  and  the  corresponding  die  selected.  The  surface  of  the  die  should 
then  be  slightly  oiled,  and  the  gold  cut,  annealed,  and  placed  over  it,  and 
then  adjusted  to  position  in  the  "stamper."  A  buckshot  or  piece  of  lead 
of  suitable  proportions  should  then  be  placed  upon  the  gold,  and  the 
plunger  of  the  "stamper"  brought  in  contact. 

The  plunger  is  held  quite  securely  in  any  position  by  means  of  fric- 
tional  contact,  which  facilitates  the  swaging  in  preventing  the  rebounding 
of  the  die,  or  the  slipping  or  moving  of  the  gold  or  lead  during  the  pro- 
cess of  driving  it  down  by  the  use  of  a  swaging  hammer. 

A  special  die,  containing  two  depressions  of  different  sizes,  is  pro- 
vided for  improving  the  occlusion  when  indicated,  by  lengthening  or 
deepening  the  cusps  at  any  desired  point.  After  the  cusps  have  been 
swaged,  the  point  to  be  raised  or  deepened  should  be  placed  over  the  hole, 
and  further  swaged  to  the  necessary  extent  by  the  use  of  a  blunt  piece  of 
wood  of  suitable  size. 

Baird  System. 

Another  recent  device  in  this  line  is  the  system  and  method  designed 
by  Dr.  W.  H.  Baird. 

This  consists  of  a  heavy  pair  of  swaging  pliers,  with  parallel  jaws, 
one  of  which  is  grooved  to  admit  of  slides  which  support  the  dies. 

The  dies  are  raised  and  individual  in  character,  made  of  a  compara- 
tively indestructible  inetal,  and  include  about  two  hundred  and  fifty  mod- 
erately good  forms.    These  comprise  a  good  selection  of  cusp-forms,  and 


103 

a  proportionate  number  of  the  buccal  surfaces  of  bicuspids  and  molars, 
and  the  labial  and  lingual  surfaces  of  the  anterior  teeth. 

When   the   selection  of   the   form  calculated   to 

Application.  best  meet  the  requirements  has  been  made,  it  is  then 

placed   in   position  on   the   slide,  and  the  latter  ad- 
justed to  the  grooves  in  the  pliers. 

The  gold  is  then  annealed,  placed  upon  the  die,  and  covered  with  a 
pad  of  soft  rubber,  or  piece  of  sheet  lead  of  adequate  thickness  f  about  3-16 
of  an  inch),  and  dimensions,  to  serve  as  a  counter-die.  The  pliers  are 
then  closed  and  held  together  with  sufficient  firmness  to  prevent  any  re- 
bound during  the  process  of  swaging,  which  is  accomplished  with  a 
hammer. 

The  flat  base  to  each  die  precludes  any  opportunity  for  accurately 
adjusting  to  the  band,  in  making  the  selection;  and  the  system  affords 
no  provision  for  altering  the  cusp  reproductions  to  more  perfectly  meet 
the  requirements  of  occlusion,  depending  upon  the  varietv  and  general 
application  of  the  dies  for  this  ]:)urpose. 

Seamless  Itletbod. 

The  seamless  method  comprises  forming  the  entire  crown  with  one 
piece  of  gold,  by  swaging,  and,  while  many  systems  for  this  particular 
style  of  construction  have  been  devised,  and  are  used,  a  close  observation 
of  the  relative  advantages  and  disadvantages  as  compared  with  the  sec- 
tional method  fails  to  afford  any  real  or  practical  evidences  of  special 
merit  in  this  process. 

It  is  claimed  by  those  using  and  advocating  this  method  that  a  closer 
reproduction  of  the  natural  tooth  form  is  possible,  and  that  greater  oppor- 
tunities for  more  pronounced  contouring  are  afforded,  from  which  asser- 
tions it  is  deduced  that  more  artistic  results  may  be  obtained. 

As  such  results  from  any  metJwd  of  procedure,  however,  are  equally 
dependent  upon  the  skill,  ability  and  conscientious  efforts  of  the  operator, 
and,  as  the  presence  of  a  joint  between  cusp  and  band  is  in  no  way  objec- 
tionable if  the  prerequisites  previously  mentioned  have  been  observed,  any 
actual  or  practical  foundation  for  such  a  claim  is  scarcely  apparent. 

If  it  were  still  necessary  to  depend  upon  a  limited  selection  of  cusp 
forms,  which  were  difficult  to  adapt  to  the  average  properly  contoured 
band  without  the  use  of  considerable  solder  and  much  filling  in,  some  ad- 
vantage might  be  possessed  by  a  method  which  would  afford  a  smooth 
continuous  crown,  but,  in  view  of  the  possibilities  already  outlined  in  this 
connection,  the  real  value  of  the  seamless  method  will  doubtless  always 
remain  more  appreciable  to  the  "dental  laboratories,"  and  others  commer- 
cially interested,  than  to  the  average  practitioner  of  ordinary  skill. 


I04 

A  summary  of  the  possible  advantages  of  this 

Jfdvantases.  method  presents  but  two  special  features  :    First,  the 

opportunities  for  obtaining  contour,  and,  second,  the 
absence  of  a  joint  or  seam  of  solder  at  any  point. 

The  first  feature  needs  no  consideration,  because,  as  has  been  pre- 
viously asserted,  the  possibilities  of,  and  opportunities  for,  contouring, 
are  not  entirely  dependent  upon  the  process  employed,  and  in  no  way  ex- 
ceed those  offered  by  the  sectional  method  in  so  far  as  the  actual  require- 
ments are  concerned. 

In  considering  the  second  feature,  the  absence  of  a  joint  or  seam  of 
solder  may  be  proclaimed  as  an  advantage  in  three  instances  of  detail. 
First,  in  eliminating  the  possibilities  of  the  subsequent  discoloration  of  the 
solder  in  the  joint,  when  subjected  to  the  action  of  the  secretions.  Second, 
in  the  construction  of  a  platinum  crown  which  is  to  serve  as  an  abutment 
for  porcelain  bridgework.  Third,  in  the  construction  of  a  gold  crown  for 
the  bicuspids  where  a  porcelain  facing  is  to  be  subsequently  in- 
serted. 

In  the  Urst  instance,  if  the  edges  to  be  united  are  closely  -fitted  and 
approximated,  the  quantity  of  solder  in  the  joint  is  so  infinitesimal  that 
if  a  high  grade  of  similar  color  be  used,  and  the  crown  then  well  finished 
and  polished,  no  opportunity  will  be  offered  for  any  subsequent  discolo- 
ration ;  hence,  no  special  advantage  is  apparent. 

In  the  second  instance  the  same  advantage  may  be  readily  obtained 
by  permanently  overlapping  the  edges  of  the  band  in  making  the  joint, 
and  closely  approximating  the  edges  of  cusp  and  band,  and  then  using- 
platinum  solder  in  their  union.  This  will  preclude  the  re-fusing  or  un- 
soldering of  the  parts  in  the  furnace  daring  the  process  of  fusing  the 
porcelain ;  and  the  additional  thickness  of  platinum  which  may  be  used 
when  the  sectional  method  is  employed  adds  materially  to  the  necessary 
strength  which  such  a  crown  must  possess  in  that  particular  portion  of  it 
zvhich  surrounds  the  root. 

In  the  third  instance  the  advantage  is  perhaps  least  imaginary,  but  if 
the  joints  of  the  sectional  crown  intended  for  such  a  purpose  are  made  as 
has  been  indicated,  the  subsequent  attachment  of  the  facing  with  a  lower 
grade  of  solder  may  be  done  without  danger  of  re-fusing  them.  This  may 
be  also  further  prevented,  if  any  doubt  exists,  by  previously  coating  the 
solder  in  such  joints  with  a  solution  of  whiting  in  water  or  alcohol  before 
attaching  the  facing. 

The  features  of  this  style  of  construction  which 

Di$(ldvantildC$.         are  of  a  more  or  less  pronounced  disadvantage,  in  a 
general  way,  lie  in  a  consideration  of  the  essentials  of 
time,  strength  and  accuracy  of  adaptation. 


I05 

The    detail    being    more    circuitous,    a    greater 

Z\mt,  length  of  time  is  necessarily  consumed  in  the  process. 

If  better  results  by  this  method  than  by  any  other 

were  possible,  this  should  not  necessarily  be  a  consideration,  but  it  Ijecomes 

a  matter  of  much  concern  when  equally  good  results  may  be  obtained  by 

another  method  in  less  time. 

The  fact  that  a  much  thinner  gauge  of  metal 
Strength.  must  be  used  to  begin  with,  and  that  it  must  then  be 

subjected  to  considerable  stretching,  is  conspicuously 
a  disadvantage,  because  of  the  extreme  thinness  and  consequent  weak- 
ness of  the  finished  crown.  While  sufficient  re-enforcement  of  the  occlusal 
portion  rnay  be  afterward  made,  the  band,  where  equal  and  uniform 
strength  is  usually  required,  must  remain  inherently  weak,  or  be  stiffened 
at  the  expense  either  of  the  root  or  of  the  contour. 

As  a  degree  of  accuracy  must  be  insurefl  in  the 
JIdaptation.  process,  the  adaptation  to  the  root  of  a  primary  or 

temporary  band  is  necessary.  This,  however,  in  one 
particular  is  a  disadvantage,  because,  irrespective  of  however  accurate  it 
may  be,  each  subsequent  reproduction  of  a  given  form  is  less  accurate  than 
the  original,  unless  they  may  be  stamped  in  indestructible  and  unyielding 
dies,  which  equalities  are  not  possessed  by  fusible  alloys,  such  as  are  used 
for  the  dies  in  this  work. 

Detail  of  €on$tnictiOH. 

While  there  are  many  and  varied  methods  of  detail  for  the  construc- 
tion of  seamless  crowns,  but  one  general  line  of  procedure  will  be  found 
to  give  results  which  are  sufficiently  reliable  to  insure  an  approach  to  the 
necessary  degree  of  accuracy. 

This  constitutes  taking  a  measurement  of  the  root,  after  its  prepara- 
tion, and  making  and  fitting  a  primary  band,  the  exact  shape  and  con- 
formation of  which  is  then  subsequently  reproduced  in  the  finished  crown. 

The  primary  band  may  be  made,  preferably,  of 
Primary  Band.  32  gauge  copper,  cut  to  ordinary  width,  the  exact 
length  of  the  measurement,  with  straight  edges,  and 
soldered  as  usual.  Or  a  seamless  band  may  be  made  by  selecting  the 
drawing  punch  over  which  the  circular  measurement  will  fit  most  closely,- 
and  then  drawing  a  blank  down  to  this  same  size.  By  then  punching  out 
the  top,  a  seamless  band  results,  which  approximates  the  size  of  the  root 
as  closely  as  the  measurement  fitted  the  punch.  Those  preferring  the  latter 
usually  have  a  selection  of  these  blanks  already  drawn  to  various  sizes, 
which  is  an  economy  of  time. 

When  the  band  has  been  made,  it  should  be  trimmed  and  fitted  to  the 


io6 

root  with  the  same  degree  of  care  and  precision  as  though  it  were  intended 
for  permanent  use.  It  should  then  be  cut  away  upon  the  buccal  and  lingual 
surfaces  until  but  a  narrow  rim  remains,  allowing  the  approximal  surfaces 
to  remain  sufificiently  wide  to  be  closely  adapted  to  the  adjacent  teeth. 
(Fig.  90.)  By  so  shaping  it,  a  perfect  restoration  of  the  contact  points 
may  be  made,  and  increased  opportunity  is  afforded  for  forming,  shaping, 
modifying  or  exaggerating  the  buccal  and  lingual  surfaces  as  may  be 
desired. 

I  When  the  fitting  and  trimming  has  been  com- 

BWC  and  Tm^jresslOlt.    pleted,  the  bite    and    impression    should    be    taken. 
While  this  is  often  done  at  one  and  the  same  time, 
with  wax  or  modeling  compound,  a  separate  bite  in  wax,  and  impression, 
in  plaster  is  preferable,  and  safer,  because  of  the  uncertainty  of  replacing 
the  band  in  its  exact  and  proper  position  in  the  former  materials. 

When  these  have  been  secured,  and  the  band  accurately  replaced  in 
position  in  the  impression,  the  model  should  be  obtained,  the  bite  adjusted 


fiq.  90. 


Ficj.91. 


to  it,  and  both  securely  mounted  upon  the  articulator.  After  separating, 
the  surfaces  of  the  adjacent  and  occluding  teeth  should  be  varnished  and 
the  band  and  space  filled  with  thin,  well-mixed  plaster,  and  the  articulator 
firmly  closed. 

This  portion  of  the  procedure  and  the  subsequent  carving  and  shap- 
ing of  the  plaster  is  almost  identical  with  the  detail  previously  outlined  in 
carving  cusps,  and  all  of  the  necessai  /  artistic  work  must,  of  course,  be 
done  at  this  stage,  because  the  permanent  crown  will  be  a  close  reproduc- 
tion of  this  model. 

The  only  difference  in  the  detail  is  that  the  form  and  alignment  of 
buccal  and  lingual  surfaces  is  obtained  by  shaping  the  plaster,  instead  of 
contouring  the  wider  band,  and  that  it  should  be  done  zvithouf  detaching 
the  band  from  the  model,  and  also  that  the  plaster  should  be  left  flush, 
even  and  continuous  with  the  band,  instead  of  being  trimmed  to  expose 
its  edge  as  for  a  swaged  cusp. 


i07 

When  the  necessary  carving  has  been  completed, 
Prcparlnfl  models,     the  model  should  be  detached  from  the  articulator, 
and  trimmed  down  until  only  enough  remains  to  form 
a  base  for  the  crown,  as  indicated  in  Fig.  91. 

This  plaster  base  is  then  trimmed,  so  as  to  be   favorable  for,  and 
facilitate  handling  during  the  process  of  securing  the  die,  and  to  give 


(Half  Size) 

adequate  depth  or  body  to  the  latter.  The  plaster  base  immediately  ad- 
jacent to  the  cervical  portion  of  the  band  should  be  cut  away  sufficiently 
to  expose  the  full  thickness  of  the  edge,  which  thus  stands  out  in  the  die 
and  indicates  the  outline,  after  swaging,  to  which  the  finished  crown 
should  be  trimmed.     (Fig.  92.) 

Various  designs  of  casting  flasks  have  been  de- 
Castiltd  TIaskS.        vised  for  the  purpose  of  serving  as  a  matrix  in  se- 
curing the  dies  with  fusible  alloy.     Much  similarity 
of  principle  exists  between  them  all,  and  the  one  which  is  a  part  of  the 


Seamless  Crown  Outfit,  manufactured  by  the  Consolidated  Dental  Manu- 
facturing Company  (Fig.  93),  is  simple  and  conveniently  adequate  for 
such  purposes;  though  those  designed  by  Dr.  W.  H.  Trueman  (Fig. 
94a)  (which  must  be  held  in  a  vise  while  swaging),  and  the  Berry  Dental 
Manufacturing  Company  (Fig.  94b),  will  be  found  to  favorably  meet 
the  requirements. 


io8 

In  securing  the  die,  the  plaster  model  containing 

Dies.  the   crown   should  be    thoroughly   dried^  to   prevent 

any  bubbling  of  the  metal,  dusted  with  lycopodium, 

and  then  placed  on  a  smooth  level  surface  of  steel  or  mouldine,  so  as  to 

rest  firmly  and  sustain  a  perpendicular  position  and  the   casting   flask 

placed  over  and  around  it. 

A  piece  of  thin  cardboard  should  be  adjusted  to  the  grooves  in  each 
side  of  the  flask,  and  trimmed  to  follozv  the  outline  oi  the  model  (Fig.  95) . 
These  are  intended  to  facilitate  the  subsequent  separation  of  the  die  into 
two  lateral  halves,  but  should  not  come  in  contact  with  the  model  at  any 
point. 

The  flask  should  then  be  filled  with  fusible  alloy,  poured  when  in  the 


Fj<^.95 


plastic  state,  in  order  to  insure  a  smooth,  well-defined  casting,  and  to 
facilitate  the  separation  of  the  crown  from  it. 

Another  method  is  to  first  fill  the  flask  with  the  molten  alloy,  after, 
adjusting  the  cardboard,  and  then  firmly  force  the  model  into  the  center 
of  the  metal  just  before  the  process  of  crystallization  takes  place,  holding 
it  in  position  until  it  has  thoroughly  hardened.  Tf  done  just  at  the  right' 
moment,  this  method  is  productive  of  good  results,  but  the  procedure  is 
somewhat  more  uncertain  than  the  former. 

After  chilling  the  metal  with  cold  water,  it  should  be  removed  from 
the  flask  and  the  cardboard  detached.  By  inserting  a  chisel  into  one  of 
the  grooves  thus  formed,  and  striking  it  a  moderate  blow,  the  die  may  be 
easily  separated  into  two  parts.  (Fig.  96.)  The  model  is  now  removed 
from  the  die,  and  the  parts  may  be  readjusted  to  proper  relation,  and  re- 
placed in  the  flask,  which  possesses  a  guiding  notch  to  insure  proper  read- 


I09 

JLislnient,  and  which  liolds  them  securely  together  during  the  process  of 
swagii^g  the  crown. 

The  seamless  l^lank,  or  cartridge,  which  is  to  he 
Terming  Blanks.      conformed  to  the  desired  outline  of  the  permanent 

crown,  hy  swaging,  should  now  be  formed. 
For  this  purposes  all  of  the  ''Systems"  or  "Outfits"  contain  or  include 


Ficj.96. 

a  steel  plate  with  perforations,  the  diameters  of  which  range  consecutively 
from  the  largest  to  the  smallest  useful  sizes,  with  a  set  of  steel  punches 
correspondingly  graded. 

A  disk  of  22  karat  gold,  not  thicker  than  30,  or  thinner  than  32  gauge, 
should  be  procured.  These  are  prepared  by  the  supply  houses  in  various 
sizes.     The  two  sizes  most  convenient  for  molars  and  bicuspids  are  illus- 


//•y.97. 


trated  in  Fig.  97  and  may  be  symmetrically  cut  from  plate  by  using  an 
accompanying  copper  disk,  or  the  end  of  a  drawing  punch  as  a  guide. 
These  disks  are  formed  into  the  blank  by  driving  them  through  the 
holes  in  the  plate  with  the  drawing  punches,  beginning  with  the  largest 
size  and  passing  through  each  consecutive  perforation  until  the  blank  is 
reduced  to  a  size  which  will  admit  of  its  being  gently  forced  into  the  die. 


no 

If  a  seamless  primary  band  has  been  used,  the  size  of  the  drawing 
punch  last  used  in  its  formation  will,  of  course,  indicate  the  size  of  the 
blank  required  for  the  crown,  and  the  size  or  number  should  be  desig- 
nated or  remembered. 

The  gold  should  be  annealed  often  during  the  process  to  prevent 
tearing,  and  slightly  oiling  the  end  of  the  punches  and  the  interior  of  the 
perforations  will  be  found  advantageous  in  facilitating  the  drawing  and 
preventing  the  blank  from  sticking  to  the  former. 

The  drawing  press  designed  for  this  purpose  by  Dr.  W.  M.  Sharp 
may  be  found  useful.  It  can  be  securely  fastened  to  the  bench  and  the 
blank  is  formed  by  means  of  a  screwpress  instead  of  driving,  which  re- 


sults in  its  being  drawn  more  evenly  and  uniformly  than  by  intermittent 
blows. 

When  the  blank  has  been  formed  to  the  desired 

Swaging*  size,  it  should  be  cleaned  in  the  acid  bath,  and  then 

annealed.     The  surface  of  the  die  should  be  oiled 

and  the  blank  gently  forced  well  down  into  place  with  a  blunt  piece  of 

soft  wood  of  suitable  size,  and  a  small  hammer. 

Any  excessive  surplus  of  band  may  be  previously  trimmed  away  to 
facilitate  swaging,  but  care  should  be  exercised  not  to  trim  too  much. 

The  interior  of  the  blank  should  be  filled  with  a  substance  which  will 
spread  readily  and  evenly  when  pressure  is  applied,  but  which  may  be 
easily  removed  at  any  time  during  the  process. 

Oiled  birdshot,  cornmeal,  pumice  stone,  small  cubes  of  modeling  com- 
pound, base-plate  gutta  percha  cut  into  small  pieces,  pledgets  of  moistened 
cotton,  or  cotton  previously  saturated  with  melted  wax,  stiff  putty  mixed 
with  soapstone  and  tin  foil  rolled  into  small  globules  are  used. 

The  swaging  is  then  accomplished  by  driving  a  blunt  piece  of  wood, 
or  the  end  of  a  drawing  punch  a  few  sizes  smaller,  into  the  blank  thus 


Ill 

filled.  If  necessary,  the  gold  may  be  removed  and  annealed  several  times, 
though  once  after  starting  and  during  the  process  is  all  that  is  usually 
required. 

When  the  swaging  has  been  completed,  the  sur- 

Jldaptina  plus  should  be  trimmed  away  to  closely  follow  the 

and  Rc-Cnforclttfl,       cervical  outline  indicated  in  the  band,  and  the  crown 

sUglifly  heated  and  subjected  to  the  acid  bath,  when 

it  may  be  re-enforced  with  a  high  karat  of  solder  or  a  lower  karat  uf 

plate  gold,  rolled  lliui,  and  finished. 

If  the  finished  crown  should  be  too  large,  it  may  be  reduced  with 
pliers  before  re-enforcing,  or  if  iiiucli  too  large  as  a  result  of  compressing 
the  walls  of  the  die  during  the  process  of  swaging,  it  may  be  first  cut  in 
two  lateral  halves,  left  in  the  die,  and  another  crown  swaged  inside  of  it ;  or 
if  too  small,  which  is  rarely  the  case,  it  nia_\'  be  stretched  sufficiently  with 
pliers.  Where  some  expanding  or  compressing  of  the  bulbous  portion  may 
be  indicated  in  order  to  improve  the  contact  with  adjacent  teeth, the  rotary 
point  contouring  pliers  designed  bv  Dr.  C.  W.  Miller  will  be  found  useful 
(Fig.  98). 

While  many  of  the  various  "systems"  provide  means  for  securing 
the  model  from  a  selection  of  typical  forms  of  approximate  sizes,  from 
which  the  dies  are  made ;  and  for  securing  the  outline  of  the  occlusal  sur- 
face by  subsequently  swaging  in  a  typical  die-plate,  or  other  similar  man- 
ner, the  possible  results  obtained  from  such  methods  do  not  merit  con- 
sideration because  of  being  but  little,  if  any,  more  accurate  than  ordinary 
readv-made  crowns. 


J(ivtr$t  Process. 

In  the  preceding  process  it  v\ill  be  noted  that  in  the  detail  of  swag- 
ing, the  blank  is  conformed  to  the  outline  of  a  mould  or  die  of  the  orig- 
inal model,  by  expanding  or  stretching  it.  This  is  termed  the  "inside- 
out"  method,  and,  while  it  is  perhaps  most  generally  used,  the  extrem.e 
thinness  of  the  finished  crown,  augmented  by  the  necessity  of  begin- 
ning with  so  thin  a  gauge,  verv  consistently  occasions  the  objectionable 
features  already  intimated  in  this  connection. 

As  a  means  of  overcoming  such  objections,  and  obtaining  increased 
thickness  and  strength,  the  rez'erse  or  "outside-in"  process  of  swaging 
has  been  devised. 

In  this  method  the  blank  is  conformed  by  being  compressed  over  a 
metal  reproduction  of  the  original  model,  instead  of  being  expanded  to 
meet  the  walls  of.  a  mould  of  it. 


112 

While  the  process  of  swaging  is  perhaps  more 

JldcantagC$«  difficult  to  accomplish,  the  results  are  advantageous 

in  being  productive  of  a  heavier  and  more  uniform 

thickness  of  gold  in  the  finished  crown,  and  of  greatly  diminishing,  if 

not  entirely  overcoming,  the  probability  of  tearing  it. 

The  result  obtained  by  swaging  the  gold  over 
Disadvantages.  the  outside  dimensions  of  a  metal  reproduction  of 
the  original  and  desired  form,  would  seem  to  be  ob- 
jectionable in  that  the  crown  so  conformed  must  be  somewhat  larger 
than  the  model.  This,  together  with  the  tendency  of  the  gold  to  over- 
lap and  knuckle  here  and  there,  during  the  swaging,  are  logical  disad- 
vantages, unless  means  are  observed  for  overcoming  them. 

While  the  overlapping  and  knuckling  may  be  easily  avoided  by  care- 
ful manipulation  of  the  gold  during  the  process,  the  difference  in  size 
occasioned  by  the  thickness  of  gold  can  be  overcome  only  by  using  force 


Fiq  99 


FicflOO 


enough  in  swaging  to  so  compress  the  die  by  the  impact  as  to  compen- 
sate for  this  thickness,  or,  by  removing  the  primary  band  just  previous 
to  reproducing  the  metal  model. 

In  view  of  the  characteristics  of  the  lower  melting  fusible  alloys 
which  are  necessarily  used,  and  of  the  thinness  of  the  gold  after  being 
drawn  down  to  the  recjuired  size  blank,  it  is  possible  that  fairly  accurate 
results  may  be  obtained  by  depending  upon  the  compression  of  the  metal 
model  from  the  force  and  impact  of  swaging;  yet  as  this  is  more  or 
less  uncertain,  the  removal  of  the  band  is  the  preferable  procedure  and 
will  afford  the  most  positive  and  accurate  results. 

As  the  variation  between  this  and  the  preceding 
Procedure.  method  pertains  only  to  the  manner  of  securing  the 

dies,  and  to  the  process  of  swaging,  the  procedure 
up  to  the  point  of  obtaining  the  model  is  identical  with  that  already  out- 
lined. 


"3 


When  the  crown  lias  Ijeen  removed  from  the  artic- 

Origlnai  mcd«l.        ulator,  and  its  plastor  base  trimmed  to  the  required 

form  as   previously   indicated  in   Fig.  92,  it  should 

then  be  reproduced  in   fusible  alloy,  instead  of  obtaining  metal  dies  of 

it  in  the  form  of  a  mould. 

If  the  band  is  to  be  removed  from  the  model,  the  plaster  base  should 
be  trimmed  away  sufficiently  deep  so  as  to  leave  a  distinct  cervical  out- 
line to  guide  in  trimming  the  crown  after  swaging.  The  removal  of  the 
band  niav  be  easily  accomplished  b>  cutting  through  it  at  the 
narrowest  and  most  convenient  point,  with  a  fine  saw  or  file,  after 
which  the  entire  plaster  outline  should  be  nicely  smoothed  down,  and 
then   varnished. 

The    mould    is    obtained    in    the    same    manner 
mould.  formerl}-    pursued    in    securing    the    dies,  excepting 

that  it  is  made  of  plaster  in- 
stead of  metal.  The  varnished  model  should  be 
adjusted  to  the  casting  flask,  or  similar  device, 
with  pieces  of  cardboard  /;;  situ,  Fig.  95,  and  thin 
plaster  then  poured  upon  it.  After  crystallization 
this  may  be  broken  open,  the  model'removed,  and 
,  Ihe  parts  replaced  and  adjusted  to  the  flask. 

When  the  plaster  has  be- 
Swaging  model.  come  sufficiently  dry,  this 
should  be  filled  with  fusible 
alloy  which  melts  at,  or  below,  the  temperature 
•of  boiling  water.  The  metal  model  thus  resulting. 
Fig.  99,  is  identical  with  the  original  model,  and 
over  this  the  blank  of  gold  is  conformed  by  vari-  f/q  101 

■ous  processes  of  swaging. 

After  drawing  the  blank  to  a  size  which  will  fit 
Blanks.  snugly    over    the    swaging   model,    or    securing    the 

same  from  the  supply  houses  in  ready-made  form,  it 
should  be  first  thoroughly  annealed,  as  any  subsequent  annealing  is  pre- 
vented after  the  swaging  has  been  started,  because  of  the  necessity  for 
the  destruction  of  the  swaging  model,  by  melting  it.  to  admit  of  the  re- 
moval of  the  blank. 

In  conforming  the  blank  to  the  outlines  of  the 
Swaging.  swaging  model,  considerable  care  must  be  exercised 

to  prevent  knuckling  and  overlapping  of  gold  by  any 
method  employed.  This  can  only  be  accomplished  by  frequently  remov- 
ing the  crown  and  working  out  such  places  with  a  small  riveting  ham- 
jner.  Fig.  100. 


114 

While    several    systems   and   devices   have   been 

niCtbOdS.  designed  for  the  purpose  of  swaging  crowns  by  this 

process,  the  cylinder  and   plunger  are  the  essential 

features  of  the  most  useful  ones,  and  even  hydraulic  pressure  may  be  very 

serviceably  employed. 

Ash's  crown  swaging  device  can  be  made  to  answer  the  purpose  by 
boring  out  the  end  of  the  plunger  until  it  presents  the  form  of  a  cone 
equal  in  depth  to  that  of  the  average  crown,  and  a  similar  apparatus  es- 
pecially designed  to  meet  such  requirements  constitutes  a  portion  of  the 
seamless  crown  outfit  manufactured  by  Mr.  J.  W.  Place,  of  New  York 
City.  The  cone  shape  plunger  is  necessary  in  order  to  distribute  the  im- 
pact evenly  over  the  entire  surface  of  the  crown. 


fjrr  102 


In  the  use  of  such  devices  the  blank  should  first  be  fitted  over  the 
swaging  model  and  gradually  worked  down  to  place  with  the  riveting 
hammer.  This  should  be  placed  in  the  center  of  the  cylinder  and  oiled 
1:)ird-shot  or.  preferably,  stiff  putty  freely  mixed  Avith  lycopodium  or  soap- 
stone,  then  packed  closely  around  and  over  it  until  entirely  submerged. 
The  plunger  should  now  be  inserted  and  gradually  driven  to  place,  re- 
moving the  crown  frequently  and  working  out  the  overlaps,  until  the 
swaging  is  completed. 

The  apparatus  designed  by  Dr.  W.  P.  Scott,  of 
Scott's  method.        Chicago,  which  consists  of  an  inverted  cone  shaped 
cylinder,  and  straight  flat-surface  plunger,  \\ith  other 
necessary  accoutrements,  is  among  the  most  complete,  simple  and  mod- 
ern inventions  for  this  work,  though  it  is  similar  to.  and  used  much  in 
same  manner  as  the  Berry  and  Adam  son  outfits. 

In  the  use  of  this  system  the  blank  is  fitted  to  the  swaging  model 
as  indicated,  and  the  occlusal  surface  first  swaged  by  driving  the  same 
into  a  surface  of  lead.  After  this  portion  of  the  crown  is  adequately 
swaged,  it  is  then  placed  in  a  matrix  afforded  between  the  two  surfaces 
of  lead    which  are  formed  in  a  mould  accompanying  the  outfit,  and  the 


whole  then  dropped  into  the  cyHnder.  The  base  and  top  of  tlie  latter 
are  adjusted,  and  the  plunger  inserted,  (Fig.  loi,)  which  upon  being 
driven  deeper  into  the  cylinder  so  compresses  the  lead  matrix,  and  the 
gold  blank,  as  to  closely  conform  it  to  the  outlines  of  the  swaging  model, 
with  a  minimum  tendency  to  tear  or  overlap,  and  with  a  maximum  and 
uniform  increase  in  the  thickness  of  the  gold.  The  lead  matrix  before 
and  after  swaging,  together  with  the  crown  in  position  in  the  latter,  are 
illustrated  in  Fig.  102. 

When  the  swaging  has  been  adequately  accom- 
TiniSbiltfl.  plished  by  the  method  selected,  very  little  finishing 

is  usually  required.  The  crown  should  be  polished 
before  detaching  it  from  the  metal  model,  after  which  the  latter  should 
be  melted  by  placing  in  boiling  zvafer,  and  any  adhering  or  remaining 
particles  removed  by  the  acid  bath.  The  surplus  gold  at  the  cervical  por- 
tion should  then  be  carefully  trimmed  away  to  follow  the  outline  indi- 
cated, when  the  necessary  reinforcement  and  final  polishing  may  be 
given. 


Ficf.104-. 

Jlpplicdtioii  to  Separatca  molar  Roots. 

The  presentation  of  cases  where  molar  roots  have  become  separated 
at  the  bifurcation  as  the  result  of  extensive  disintegration  of  the  crown, 
and  with  each  individual  root  remaining  Urm  in  its  attachment,  is  not  an 
infrequent  or  unusual  occurrence. 

In  such  instances  the  application  of  a  crown  will  not  only  often 
restore  the  roots  to  the  former  usefulness  and  supply  the  serviceability  of 
the  original  tooth  for  many  years,  but  will  also  frequently  preclude  the 
Impaired  occlusion  of  the  adjacent  teeth  which  their  natural  gravitation 
or  tipping,  as  the  result  of  the  loss  of  such  roots,  would  occasion. 

This  latter  phase  places  a  degree  of  importance  upon  the  permanent 
retention  of  these  roots,  which,  particularly  in  early  life,  and  especially  on 
fi,rst  molars,  makes  such  a  procedure  of  inestimable  value,  and  causes  it  to 
be  almost  universally  indicated  wherever  such  a  condition  is  found  in 
otherwise  unbroken  or  well-filled  arches,  with  the  roots  remaining  rea- 
sonablv  firm. 


ii6 

In  the  treatment  of  these  cases   the  individual 

Procedure.  roots  should  be  carefully  prepared  by  observing  the 

therapeutic  and  mechanical   requirements,   and   each 

then  built  up  separately  with  amalgam  (anchored  with  a  post,  or  by  other 

mechanical  retention)  until  they  afford  favorable  shape  for  the  permanent 

attachment  of  a  band.      (Fig.  103.) 

Separate  bands   should   be  fitted  to  each,   their 
Bands.  occlusal  ends   trimmed   to  allow   for  the   cusp,   and 

contoured   to   approximate    each   other,   and   restore 
contact  with  adjacent  teeth. 


nq.105. 

The  usual  bite  in  wax. and  impression  in  plaster  should  be  secured, 
and  the  case  finally  mounted  upon  the  articulator.  After  separatmg,  and 
detaching  the  bands  from  the  model  in  such  manner  as  to  preserve  their 
outline  and  admit  of  accurate  replacement,  they  should  be  readjusted  to 
the  model  and  united  secureh'  together  with  hard  wax ;  then  they  may 
be  removed  and  the  ciTT'/ra/. one-half  imbedded  in  investment  material. 
Their  relation  may  now  be  permanently  sustained  by  filling  in  between 


Ficj. 


106. 


them  With  22  karat  solder,  which  union,  involving  the  occlusal  ends  only, 
will  leave  a  free,  clean  interproximal  space.      (Fig.   104.) 

The  united  bands  may  now  be  replaced  upon  the 

Cusps.  model  and  the  cusps  formed  in  the  usual  manner,  as 

though   for  the  single  band  of   an  ordinary  crown. 

In  attaching  them,  however,  care  must  be  exercised  to  prevent  re-fusing 

the  solder  with  which  the  bands  were  previously  luiited,  and,  thus  cliang- 


ing  or  destroying  the  relation  between  them.  The  use  of  a  lower  grade 
solder  will  ordinarily  preclude  this,  but  to  further  facilitate  it  the  cusps 
should  be  filled  with  solder  after  obtaining  their  proper  adaptation,  and 
previous  to  attaching  them  to  the  bands.  Very  little  danger  will  then 
exist,  and  any  may  be  entirely  overcome  by  the  use  of  a  solution  of 
whiting  and  alcohol,  which  precaution  it  is  well  to  observe. 

Jipplication  to  Tndiv^idudl  Roots. 

Where  but  a  single  root  remains  or  possesses  sufficient  strength,  and 
particularly  in  the  lower  jaw,  it  may  often  be  retained  and  made  service- 
able for  a  number  of  years  by  the  application  of  a  crown.  Also,  in 
instances  where  such  a  root  may  be  unusually  strong,  and  the  space 
formerly  occupied  by  the  normal  tooth  has  become  lessened  or  partially 
closed  as  a  result  of  the  loss  of  the  other  root  and  the  gra^•itation  of  the 
adjacent  teeth,  it  is  often  practical  to  extend  the  occlusal  portion  of  the 
crown  until  it  rests  against  the  adjacent  tooth,  and  thus  affords  a  con- 
tinuous masticating  surface.  (Fig.  105.)  The  contact  point  between 
such  a  crown  and  the  natural  tooth,  however,  should  be  only  sufficient  to 
prevent  tipping  of  the  root  from  the  stress  of  mastication,  and  for  prophy- 
lactic reasons  should  rest  close  to  the  occlusal  surface  and  be  smooth 
and  well  rounded. 

Cantilever  Bridges. 

A  small  intervening  space  between  two  artificial  crowns  may  be 
bridged  over  until  an  unbroken  masticating  surface  presents,  by  applying 
these  same  principles,  as  Avas  originally  suggested  by  Dr.  J.  N.  Farrar. 
(Fig.  106.)  Such  a  procedure  would  be  most  practical,  however,  in  cases 
where  a  very  small  space  existed,  as  one  sufficiently  large  to  accommodate 
a  dummy  could  usually  be  best  filled  by  constructing  an  assembled  bridge. 

Jlpplicatioit  of  :Httial9atn. 

Amalgam  is  sometimes  employed  in  the  restoration  of  badly  broken 
down  molar  roots  by  crowning,  and,  while  good  results  in  the  line  of  expe- 
ditious operations  combined  with  a  moderate  degree  of  preservation  and 
permanency  are  probably  possible,  any  method  possessing  only  the  advan- 
tages of  time  and  cost  of  production,  and  requiring  less  skill  and  effort 
than  a  manifestly  better  and  more  artistic  one,  should  very  naturally 
occupy  the  limited  sphere  of  application  and  usefulness  accorded  to  this. 

In  conditions  and  environments,  however,  which  seem  to  indicate  the 
application  of  such  methods,  it  is  possible  to  obtain  fairly  good  results  in 
the  restoration  of  the  crowns  of  second  and  third  molars,  where  the  occlu- 
sion is  very  close^  by  either  of  the  following  procedures : 


ii8 

Where  a  permanent  band  may  seem  indicated  as 

mitb  Band.  a  means  of  supporting  the  remaining-  walls   of  the 

root,  and  to  aid  in  the  retention  of  the  amalgam,  it 

should  be  made  of  gold,  carefully  fitted  and  adapted,  and  then  polished 

and  cemented  to  place. 

Provisions  should  then  be  made  for  securely  retaining  the  amalgam. 
This  may  be  accomplished  either  by  means  of  a  post,  cemented  into  one 
of  the  canals,  or  by  cutting  a  mechanically  retaining  cavity  if  sufficient 
tooth  structure  remains. 

Very  plastic  amalgam  should  then  be  packed  thoroughly  to  place, 
and  built  up  to  the  desired  cusp  formation,  until  a  favorable  occlusion  is 
obtained. 

After  crystallization,  and  preferably  at  a  subsequent  sitting,  the 
amalgam  cusps  should  be  well  finished  and  polished ;  and,  while  the  gold 
band  will  have  assumed  the  same  color  by  the  superficial  absorption  of 
mercury,  its  original  color  may  be  brought  back  by  polishing,  if  desired. 

If  a  permanent  band  is  not  desired,  or  seemingly 

UlitbOUt  Band.  unnecessary,  the  entire  crown  may  be  made  with  the 
amalgam.  In  this  procedure  a  temporary  band  of 
thin  German  silver,  32  to  34  gauge,  should  be  made  and  adapted  to  the 
root,  as  indicated.  This  is  used  only  as  a  matrix  for  aid  in  adapting  and 
contouring  the  amalgam,  and  may  be  easily  removed  from  the  latter,  after 
its  crystallization,  by  cutting,  after  which  the  amalgam  crown  may  be 
finished  and  polished.  The  easy  removal  of  the  band  may  be  further 
facilitated  by  coating  its  inner  surface  with  vaseline  or  oil  before  inserting 
the  amalgam,  which  will  prevent  superficial  amalgamation  with  it. 

Where  extensive  destruction  mav  preclude  sufficiently  adequate  reten- 
tion for  the  amalgam,  it  may  be  first  tightly  packed  to  the  surface  of  the 
tooth  and  matrix,  and  around  the  projecting  end  of  a  aowel  temporarily 
adjusted  to  the  canal  if  the  use  of  the  same  seems  indicated, 
without  any  provisions  for  its  retention.  After  crystallization 
"both  may  be  removed,  the  band  separated,  and  the  crown  then 
finished  and  polished,  and  finally  mounted  with  cement,  after  serrating  or 
roughening  the  surfaces  of  crown  and  root.  Such  operations,  however, 
are  of  doubtful  permanency  as  compared  with  those  wherein  a  permanent 
band  is  employed. 

Jlpplicdtion  t«  tDe  JInterior  Cectb. 

While  it  is  difficult  to  conceive  of  a  practice  more  flagrantly  inartistic 
than  the  application  of  gold  crowns  to  anterior  teeth  or  roots,  as  has  been 
previously  observed,  they  are,  nevertheless,  occasionally  employed. 


119 

In  view  of  the  opportunities  for  more  artistic  endeavors,  and  the  in- 
creasing appreciation  of  and  demand  for  the  same,  this  class  of  gold  crown 
is  now  the  exceptional  expedient  rather  than  the  common  practice. 
and  would  douhtless  soon  hecome  entirely  (jhsolete  were  it  not  for  a 
iimitcd  class  of  cases  in  which  the  requirements  and  environments  seem  to 
justify  such  a  procedure. 

Their  application  in  any  event,  including  even  these  exceptional  con- 
ditions, should  he  made  with  an  honesty  of  purpose,  and  a  sense  of  profes- 
sional duty,  paramount  to  a  mere  catering  to  the  perverted,  unrefined 
vanity  of  the  vainglorious. 

The  class  of  cases  in  which  their  application  is 

Tn^ications.  practicable  and  warrantable  is  confined  to  the  mouths 

of  men  past  middle  age,  where  they  are  partially  or 
entirely  hidden  by  the  beard.  In  such  instances  the  use  of  gold  crowns 
may  be  indicated  in  tzvo  general  classes  of  cases : 

First,  where,  from  a  more  or  less  powerful  masticating  action,  and  by 


f/cjf.  J 07. 


years  of  constant  and  continued  attrition,  the  remaining  teeth  have  become 
so  worn  down  as  to  require  restoration  with  an  absolutely  indestructible 
material.  Second,  in  crowning  the  cuspid  teeth,  when  they  are  to  serve 
as  abutments  for  bridgework,  and  where  it  is  desirable,  and  perhaps  neces- 
sary from  a  mechanical  standpoint,  to  allow  as  much  as  possible  of  the 
natural  crown  to  remain  in  order  to  secure  the  additional  strength  thus 
imparted  to  the  attachment  between  crown  and  root ;  and  where  the  prac- 
tical invisibility  of  the  work  may  not  reqtiire  any  special  effort  toward 
securing  the  more  artistic  effects  afforded  by  other  means. 

The  first  class  of  cases  are  not  uncommon  or  infrequent,  and  usually 
present  a  more  or  less  perplexing  problem.  If  an  adequate  number  of 
the  posterior  teeth  remain,  and  occlude  with  teeth  in  the  opposing  jaw,  a 
more  artistic  result  may  often  be  obtained  by  crowning  the  posterior 
teeth  in  such  a  manner  as  to  open  the  bite  sufficiently  to  accommodate 
crowns  having  porcelain   facings  on  the  anterior  teeth,   with   reasonable 


120 

assurances  of  permanency  and  usefulness.  But  in  the  event  of  the  loss  or 
absence  of  properly  occluding  posterior  teeth,  all,  or  the  greater  portion, 
of  the  work  of  mastication  may  be  thrown  upon  the  remaining  anterior 
teeth,  and  thus  preclude  the  use  of  porcelain  and  occasion  the  necessity 
for  gold,  unless  the  posterior  teeth  be  first  supplied  by  artificial  dentures. 

Fig.  107  illustrates  a  case  where  the  bite  was  opened  by  placing 
crowns  upon  the  posterior  teeth,  with  cusps  sufficiently  thick  to  withstand 
the  work  of  mastication,  and  which  thus  admitted  the  application  of  porce- 
lain-faced crowns  to  the  anterior  teeth.  Fig.  108  illustrates  a  case  where 
the  absence  of  the  posterior  teeth  indicated  the  use  of  gold  on  the  remain- 
ing anterior  teeth,  and  where  the  crowns  were  further  fortified  against 
the  stress  of  mastication  by  tipping  each  with  26  gauge  clasp-metal.     The 


use  of  the  clasp-metal  is  especially  indicated  where  both  upper  and  lower 
teeth  are  crowned  and  the  crowns  occlude  with  one  another. 

In    the    application    of    these    crowns,    several 
Proc^(3ure.  methods   are   employed.     The   requirements   of   root 

preparation,  as  have  been  outlined  in  general,  include 
securing  the  greatest  diameter  at  the  cervix  by  reducing  the  coronal  pro- 
portions, and  further  sacrificing  the  approximal,  labial,  lingual  and  incisal 
surfaces  until  the  remaining  structure  will  admit  of  properly  shaping  and 
contouring  the  crown,  when  the  measurement  should  be  taken  as  hereto- 
fore indicated.  A  band  of  28  or  29  gauge,  22  karat  gold  should  then  be 
cut  the  exact  length  of  the  straightened  measurement  wire,  and  somewhat 
zvidcr  than  the  required  length  of  the  crown. 

■      As  the  correct  adaptation  can  be  most  accurately 

Adaptation  to  the      obtained  by  fitting  directly  upon  the  root,   and  but 

motltb«  little  time  is  thus  consumed,  the  use  of  models   is 

unnecessary.   ' 

The  band  should  be  soldered,  trimmed  to  meet  the  gum  line  evenly 


i2r 


(Fig.  109,  a.),  and  tlien  forced  to  place  n\)(ju  the  njot.  \\  lien  the  cer- 
vical adaptation  has  been  completed,  the  lingual  portion  of  the  band 
should  l)e  cut  away,  following  the  original  curvature  and  outline  of  the 
tooth.  (Fig.  109,  b.)  The  labial  surface  may  now  be  contoured  with 
the  pliers  until  it  assumes  i^n^iK-r  sliai)C  and  alignment,  and  restores  con- 
tact with  adjacent  teeth,  in  which  the  artistic  results  possible  are,  of 
course,  in  proportion  to  the  degree  of  skill  displayed. 

The  incisal  end  should  now  be  trimmed  to  the  proper  length  and 
shape,  with  an  allowance  for  the  thickness  of  the  lingual  plate  to  be  sub- 
sequently attached,  and  of  the  clasp-metal  also,  should  its  use  be  desirable 
or  necessary. 

A  piece  of  gold.  s<jmewhat  larger  tlian  neces.sary,  28  to  30  gauge,  22 
karat,  should  be  adapted  to  the  lingual  portion  of  the  band,  held  in 
contact  with  pliers  or  wire,  and  soldered  from  the  inside.     fFig.  109,  c.) 


Fiq.lOQ. 


Adequate  re-enforcement  of  the  incisal  end  should  be  obtained  by 
filling  in  sufficiently  with  solder,  or  by  attaching  a  piece  of  clasp-metal, 
previously  cut  to  the  exact  size  and  shape,  along  the  edge. 

The  surplus  should  be  cut  away,  and  the  crown  subjected  to  the  acid 
bath ;  then  finished  and  polished. 

When  it  may  become  necessary,  or  seem  desir- 

Jldaptation  able,  to  construct  the  crown  upon  models,  thus  con- 

tfr  models.  fining  the  work  to  the  laboratory,  a  narrow  primary 

band  of  copper  or  German  silver,  32  gauge,  should 

be  fitted  to  the  root,  and  an  impression,  including  the  adjacent  teeth,  then 

taken  in  plaster. 

When  this  has  been  secured,  the  band  should  be  adjusted  accurately 
to  place,  and  the  model  obtained  with  fusible  alloy,  which  is  preferable  to 
plaster,  being  more  indestructible. 

With  a  sharp  chisel  or  bur  the  outside  surface  of  the  band  on  the 
model  should  be  first  freely  exposed,  when  it  may  be  cut  in  two  and  de- 
tached. This  will  leave  the  adjacent  teeth  and  the  correct  cervical  outline 
of  the  root  definitely  exposed  in  the  model,  and  the  crown  can  then  be 
constructed  upon  it  in  the  manner  inflicated,  with  reasonable  accuracy. 


122 


Those   who   may   experience   some   difficulty   in 

(Carving  and  Swaging,    shaping  and  contouring  the  labial  surface  with  pliers 

in  an  artistic  manner,  may  be  able  to  obtain  better 

results  by  carving  and  swaging  both  labial  and  lingual  surfaces,  though 

this  method  seems  unnecessarily  circuitous. 

To  accomplish  this  the  primary  band  should  be  fitted,  the  impression 
taken,  and  a  model  secured  in  plaster.  The  band  should  be  carefully 
detached  from  the  model  and  the  latter  varnished.  With  the  band  again 
-adjusted  to  position,  the  intended  crown  may  be  formed  with  plaster, 
which,  after  hardening,  may  be  carved  to  the  desired  form.  By  the  use  of 
:mouldine  separate  dies  may  now  be  secured  of  the  labial  and  lingual  sur- 
iaces,  with  the  line  of  junction  at  the  center  of  the  approximal  and  incisal 
surfaces.     (Fig.  no,  a.) 

('         Each   surface   should    be   swaged    separately ;   the   surplus   trimmed 
away ;  the  edges  passed  over  a  flat  smooth  file  until  they  approximate 


Ficj.  I/O. 


FiqJIL 


evenly  (Fig.  no,  b.),  and  the  two  finally  soldered,  with  sufficient  incisal 
re-enforcement. 

In  this  procedure  the  degree  of  accuracy  obtained  in  the  finished 
crown  will  depend  much  upon  first  drawing  or  designatmg  a  definite  line 
between  the  two  lateral  halves  of  the  plaster  crown ;  then  securing  an 
imprint  of  each  surface  in  the  mouldine,  having  a  vv^ell  defined  edge  evenly 
approximating  this  line,  and  finally  trimming  away  the  surplus  gold, 
after  swaging,  with  care  and  precision  before  uniting  the  two  with  solder. 

The  accuracy  and  indestructibility  of  the  metal  model,  however,  sup- 
plemented by  the  definite  reproduction  of  the  diameter  and  cervical  out- 
line of  the  root,  which  is  afforded  by  the  primary  band,  aids  materially  in 
securing  the  desired  result. 

The  various  die-plate  systems  supplying  a  se- 
Di^Plate  methods,  lection  of  dies  of  the  labial  and  lingual  surfaces  may 
often  be  employed  to  good  advantage,  with  perhaps 
increased  artistic  effect,  and  a  reasonable  degree  of  accuracy,  though  they 
give  a  more  typical  reproduction  of  tooth-form  than  is  usually  necessary 
-or  required,  except  possibly  for  the  cuspid  teeth,  as  considered  in  the 
second  class  of  indications. 


123 


The  dies  for  this  purpose  contained  in  the  Lowry 
Cowry  and  ^"^1  AHllett  systems  include  only  the  labial  surfaces, 

IHillCtt  Systems.  and  may  be  used  in  accordance  with  their  application 
as  formerly  outlined.  In  their  use  the  measurement 
is  taken  and  a  band  cut  the  proper  length  and  width.  The  die  is  selected 
which  approximates  the  individual  requirements  of  the 
case,  and  the  immediate  center  of  the  band  is  then  con- 
formed by  swaging;  after  which  it  is  trimmed,  as  indi- 
cated in  Fig.  Ill,  made  in  circular  form  and  soldered.  It 
is  now  fitted  and  adapted  to  the  root,  trimmed  to  assume 
the  proper  lingual  curvature,  and  to  admit  of  the  attach- 
ment of  the  lingual  plate,  as  previously  shown  in  Fig.  109. 

The    Hollingsworth    and    Baird 
I^OllindSWOrtb  and      systems  include  separate  dies  of  both 
BaIrd  Systems.        the     labial     and     Ungual      surfaces 
mounted  on  a  single  base,  and  may 
be  used  in  similar  manner,  in  accordance  with  their  ap- 
plication, as  previously  outlined. 

When  the  die  which  most  closely  approaches  the 
requirements  for  side,  size  and  form  has-  been  selected, 
the  gold  should  be  swaged,  and  both  sides  of  the  crown 
then  trimmed  until  properly  approximated.  They  should 
then  be  wired  together,  fluxed,  and  soldered  from  the  in- 
side. (Fig.  112.)  While  it  may  now  be  possible  to  so  trim  and  shape  the 
cervical  end  as  to  secure  a  fairly  good  adaptation  to  the  root,  a  more  ac- 
curate result  may  be  obtained  by  adapting  a  narrow  band  of  gold  to  the 
root  and  then  fitting  the  crown  oz'er  it,  and  subsequently  attaching  them 
with  solder,  when  the  incisal  end  may  be  adequately  re-enforced  and  the 
crown  finished  and  polished. 

The  application  of  the  seamless  method  to  the 
Seamless  method,  restoration  of  anterior  roots  is  identical  in  detail  to 
the  procedure  previously  indicated  in  tlie  construction 
of  bicuspid  and  molar  crowns.  As  the  lingual  outline  of  the  adjacent 
teeth,  however,  will  often  serve  as  a  guide,  the  taking  of  a  "bite"  becomes 
necessary  only  when  the  opposing  teeth  may  be  irregular,  or  where  an 
incisal  or  "end  to  end"  occlusion  is  required. 

The  primary  band  should  be  made  and  fitted  in  the  manner  outlined, 
and  the  impression  secured  in  plaster.    When  the  model  has  been  obtained, 
_  the  crown  should  be  formed  and  carved,  and  the  dies  made  in  accordance 
with,  and  the  swaging  accomplished  by,  the  process  selected. 

Seamless  crowns  are  also  especially  useful  for  bicuspids  where  porce- 
lain facings  are  to  be  attached. 


124 

In  applying  this  method  to  the  construction  of 
Reproductions.  cuspid  crowns  where  the  entire  natural  crown  re- 
mains, accurate  reproductions  of  the  tooth  may  be 
quite  easily  made.  To  accomplish  this,  the  natural  crown  must  first  be 
trimmed  sufficiently  on  the  approximal  sides  to  admit  of  an  accurate  ad- 
justment of  a  band  to  the  cervix,  and,  if  necessary,  upon  the  incisal,  labial 
and  lingual  surfaces,  to  admit  of  securing  the  proper  length,  alignment 
and  occlusion.  A  narrozv  primary  band  should  then  be  fitted  to  the  neck 
of  the  tooth,  and  the  impression  and  subsequently  the  model  secured  in 
plaster.  The  plaster  tooth  should  now  be  cut  from  the  model  in  the  man- 
ner indicated  in  Fig.  91,  and  the  dies  or  swaging  model  secured  as  the 
selection  of  processes  may  require.  When  the  swaging  has  been  com- 
pleted, the  crown  will  be  a  close  reproduction  of  the  tooth  and  will  fit  it 
accurately.  Sufficient  incisal  re-enforcement  to  prevent  wearing  through,, 
however,  must  always  be  made,  even  at  the  expense  of  grinding  the  nat- 
ural crown,  if  necessary. 

This  procedure  is  sometimes  employed  without  using  the  primary 
band,  but  is,  of  course,  less  accurate,  as  the  band  indicates  the  proper  rela- 
tion to  the  root  under  and  within  the  free  margin  of  the  gum,  which  other- 
wise can  only  be  approximated  by  trimming  the  model  at  this  point. 

In  those  cases  where  the  natural  crowns  are  sa 
Dowels.  badly  worn  or  broken  down  as  to  afford  inadequate 

attachment  for  the  crown,  the  use  of  a  dowel  may 
become  necessary  as  a  means  of  supplementing  the  telescope  attachment, 
and  thus  offering  increased  integrity.  Their  application  may  be  made  by 
first  fitting  them  to  the  canal,  and  then  allowing  a  projecting  end  to  extend 
into  the  crown  as  far  as  its  incisal  edge  will  admit.  After  thus  ascer- 
taining the  proper  length,  the  dowel  should  be  previously  cemented  to 
place  in  the  root,  and  the  crown  subsequently  attached. 

Jlpplication  to  Deciduous  CeetD. 

In  some  fortunately  rare  and  exceptional  instances,  where  the  ex- 
tremely poor  character  of  the  deciduous  teeth  precludes  their  temporary 
preservation  by  other  means,  and  demands  the  employment  of  some  heroic, 
or,  perhaps,  radical  procedure  to  prevent  their  premature  loss,  the  appli- 
cation of  gold  crowns  may  be  indicated  as  the  most  simple,  expedient  and 
available  means  of  preserving  them  until  the  time  for  the  eruption  of  their 
permanent  successors. 

In  such  cases  little  or  no  preparation  would  of  course  be  possible,  or 
necessary,  and  good  results  may  often  be  accomplished  by  covering  the 
little  crowns  of  such  teeth  with  caps  made  of  pure  gold. 


T25 

In  the  procedure  a  wire  measurement  of  the  cervical  circumference 
should  be  taken,  and  then  an  impression  in  z^'a.v,  from  which  a  plaster 
model  may  be  secured,  which  will  afford  sufficient  accuracy  for  the 
purpose. 

Pure  gold  about  34  gauge  should  be  then  cut  the  length  of  the  meas- 
urement, made  in  circular  form  and  soldered,  and  then  fitted  and  shaped  as 
accurately  as  possible  on  the  model. 

It  should  then  be  finally  soldered,  with  but  little  reinforcement,  and 
finished  and  polished. 

The  tooth  should  then  be  thoroughly  disinfected,  and  the  crown 
mounted  with  cement,  and  carefully  burnished  to  a  close  adaptation  w'ith 
the  neck  of  the  tooth. 

By  this  means  this  class  of  teeth  ma}'  be  saved  until  the  proper  time 
for  their  loss  with  the  utmost  expedience,  and  without  unduly  taxing  the 
patients  of  such  tender  years. 

Ready-made  Terms. 

As  a  woful  acknowledgment  and  conclusive  evidence  of  the  lack  of 
skill  possessed  by  some,  and  of  the  ever-ready  willingness  of  the  supply- 
houses  and  commercial  dentists  to  cater  to  and  supply  the  demand,  a  large 
variety  of  ready-made  seamless  crowns,  in  gold  and  aluminum,  are  pro- 
curable ad  libitum. 

They  are  made  of  moderately  topical  form,  in  a  gradation  of  sizes,  of 
22  karat,  30  gauge  gold,  and  about  26  or  28  gauge  aluminum,  and  in  their 
use  a  measurement  of  the  root  is  taken  and  a  crown  selected  which  ap- 
proximates the  same  diameter.  The  cervix  is  then  trimmed  until  a  closure 
of  the  occluding  teeth,  with  it  in  position,  is  possible,  wdien  it  is  fitted  to 
the  root  with  pliers,  and,  if  of  gold,  re-enforced  with  solder  and  mounted. 

The  most  accurate  method  of  fitting  a  ready-made  gold  crown  to  a 
root  is  to  cut  a  slit  in  each  approximal  surface,  lap  the  edges,  place  the 
crown  on  the  natural  root  and  contract  its  cervical  circumference  by  en- 
circling the  crov/n  with  annealed  German-silver  or  copper  wire  and  twdst- 
ing  the  wire  till  the  band  is  in  good  contact  with  the  root.  Adaptation  is 
further  perfected  by  burnishing,  after  which  the  slits  are  united  with 
solder. 

That  such  crowns  may  be  correctly  adapted  to  all  the  requirements 
of  all  environments  is  doubtless  a  claim  which  no  conscientious  skil- 
ful operator  would  make,  because,  while  their  individual  formation  is 
fairly  typical  of  the  natural  teeth,  it  is  difficult  to  conceive  of  securing  a 
ready-made  form  which  can  be  adapted  to  the  requirements  of  cervical 
adaptation,  approximal  restoration,  occlusion  and  alignment,  all  combined. 
Indeed,  these  requirements  are  often  difficult  to  obtain  in  a  crown 


[26 

which  is  made  for  the  individual  case,  and  at  the  expense  of  every  degree 
of  energy,  skill  and  handicraft  possessed  by,  and  at  the  command  of,  the 
operator. 

The  progress  of  dentistry,  and  the  artistic  possibilities  pertaining  to 
it,  have  only  been  achieved  by  the  development  of  a  superior  skill  which 
cannot  be  acquired  by  the  adoption  of  such  indifferent  methods. 

Rcmovittd  and  Repairiitd* 

As  a  result  of  pathological  disturbances  arising  beneath  them,  or 
for  the  purpose  of  substitution  or  replacement,  it  not  infrequently  becomes 
necessary  to  remove  a  gold  crown  from  its  attachment  to  the  root. 

In  the  presence  of  conditions  demanding  therapeutic  treatment,  it  is 
sometimes  possible  to  cut  through  the  occlusal  surface  of  the  crown  on  a 
line  with  the  pulp  chamber,  with  a  sharp,  spear-point  drill  or  round  bur, 
and  then  enlarge  the  opening  until  adequate  access  to  the  canals  is  se- 
cured.   The  necessary  treatment  may  then  be  made  through  this  opening. 


Ficj,  113, 


upon  the  completion  of  which  the  pulp  chamber  and  crown  may  be  filled 
with  cement,  and  a  gold  filling,  anchored  in  the  cement,  subsequently  m- 
serted  until  the  opening  is  imperviously  closed. 

While  such  a  procedure  may  be  productive  of  successful  results  in 
£ome  instances,  particularly  in  bicuspids  or  single-rooted  teeth,  it  should 
not  be  regarded  as  a  saje  one  in  most  cases,  because  the  presence  of  the 
crown  only  adds  to  the  difficulties  to  be  encountered  in  an  operation  which 
is  usually  trying  enough  under  the  most  favorable  circumstances,  and  with 
every  advantage  of  access  and  light. 

For  this  reason  the  removal  of  the  crown  is  almost  invariably  indi- 
cated as  a  means  of  affording  greater  convenience  and  increased  oppor- 
tunities for  success,  and  may  be  easily  accomplished  in  two  ways. 

Where  it  is  not  necessary  to  preserve  the  con- 
0roWtt  Slitting         tinuity   of   the   band   for   subsequent   replacement   of 
forceps.  the  crown,  and  in  emergency  cases  where  its  imme- 

diate removal  is  indicated  or  demanded  as  a  means  of 
affording  relief,  the  crown  slitting  forceps  may  be  used  to  good  advan- 


127 

tage.  Those  designed  by  the  S.  S.  White  and  the  Consohdated  Dental 
Manufacturing  Companies,  the  appHcation  of  which  latter  is  shown  in 
Fig.  113,  are  especially  useful  in  securing  the  easy  and  expeditious  de- 
tachment of  the  crown  from  the  root. 

In  their  use  the  flat  beak  should  rest  firmly  upon  the  crown,  and  the 
sharpened  one  caught  just  under  the  edge  of  the  band,  when  a  slight 
compression  of  the  handles  will  quickly  separate  it.  The  band  may  then 
be  pried  away  from  the  root  with  a  smooth  flat  burnisher  until  a  pointed 
instrument  can  be  slipped  in  between  cusp  and  root  and  the  crown  lifted 
off,  which  may  also  be  often  done  with  the  forceps  alone. 

When  the  same  crown  is  to  be  replaced,  it  may 

Preserving  be  desirable  to  remove  it  without  destroying  the  con- 

Gontinuity  ©f  Band,    tinuity     and     shape    of    the    band,    thus     distorting 

its  adaptation.     This  may  be  easily  accomplished  by 

drilling  through  it  with  a  round  bur  at  a  convenient  point,  as  close  to  the 

occlusal  surface  as  the  probable  thickness  of  the  cusp  will  admit   (Fig. 


Ficf.ll4. 

114),  and  then  burring  out  as  much  of  the  cement  between  cusp  and  root 
as  possible  by  a  lateral  movement  of  the  bur.  A  stiff,  blunt-pointed  in- 
strument, similar  to  an  old  hand-plugger,  should  now  be  inserted  into 
the'  opening,  until  its  end  rests  about  on  the  center  of  the  root,  thus  secur- 
ing a  leverage  by  the  establishment  of  a  fulcrum,  when  the  crown  may  be 
lifted  off  with  but  little  effort. 

While   a   crown   removed   with   the    slitting    forceps 
Repairing  may  be  easily  repaired,  as  no  material  is  destroyed, 

it  is  doubtful  if  the  edges  so  cut  can  be  again  brought 
into  proper  relation  and  contact  without  requiring  a  readaptation  to  the 
root  in  case  of  replacement.  Aside  from  this,  the  two  procedures  may  be 
interchangeable  and  can  be  used  as  convenience  and  requirements  may 
seem  to  indicate. 

In  either  event,  when  repair  is  necessary,  all  remaining  cement  should 
be  first  removed  with  a  bur,  and  the  crown  then  thoroughly  cleaned  in 
acid,  when  the  perforations  may  be  filled  with  foil  gold,  and,  together 
with  other  openings,  then  finally  closed  with  18  karat  solder. 


tbc  Sbell  or  telescope  grovpn  in  Combination  witb  Porcelain. 


VIII. 


Indications.     Application  to  Anterior  Teeth :    Jacket    Crowns ;    Malformed    Teeth, 
Extensive  Abrasion,   Procedure;   Band,  Facing,  Backing,  Soldering.    Appli- 
cation to  Irregularities.  Application  of  Facings  to  Bicuspid  Crowns : 
Procedure;  Preparing  Crown   for     Reception     of     Porcelain, 
Adapting  Facing,  Adapting  Backing,  Soldering  Backing, 
Soldering    Facing.      Variation  of  Method.      Applica- 
tion of  Saddle-back  Teeth   to   Bicuspid   and 
Molar  Crowns:  Procedure.     Dowels. 


The  application  of  porcelain  facings  to  crown  construction,  wherein 
the  shell  or  telescope  principle  of  attachment  to  root  is  employed,  involves 
several  varied  methods  and  processes,  many  of  which  are  often  indicated 
in  special  classes  of  cases,  and  may  be  productive  of  practical  and  artistic 
results. 

While  the  modern  application  of  the  ceramic  art  doubtless  offers  far 
greater  opportunities  for  more  aesthetic  and  hygienic  achievements  in  this 
line  of  work,  the  essential  requirements  of  strength  as  applied  to  the 
method  of  attachment  to  the  root,  as  well  as  to  the  completed  crown,  are 
factors  not  infrequently  contraindicating  its  use.  These,  together  with  the 
absence  of  facilities,  or  the  lack  of  experience  and  skill,  may  often  indicate 
the  combination  of  gold  and  porcelain  as  a  means  of  obtaining  increased 
strength,  and  of  securing,  or  more  closely  approaching,  the  desired  artistic 
and  aesthetic  result. 

The  application  of  this  style  of  crown  construc- 
Tndications.  tion  is  especially  indicated  in  that  class  of  cases  where 

it  seems  desirable,  or  becomes  necessary  to  utilize  a 
portion  of  the  remaining  natural  crown  for  the  attachment  of  the  artificial 
substitute,  by  telescoping  it  instead  of  sacrificing  it  to  the  gum  line  and 
employing  a  dowel ;  and  where  the  presentation  of  porcelain  is  essential 
to  the  artistic  requirements. 

Those  conditions  in  which  these  combined  requirements  are  par- 
ticularly applicable,  and  the  preferable  and  most  practical  methods  of 
subserving  them,  will  be  considered  in  their  respective  classification. 


129 

jRpplicdtiott  to  jFInterior  Ceetb. 

The  application  of  this  style  of  crown  to  the  six  anterior  teeth,  upper 
or  lower,  is  frequently  indicated,  but  should  be  made  only  in  the  absence 
of  a  better  method,  and  in  accordance  with  the  judgment  and  discretion 
of  experience,  because  the  practicability  of  the  principles  involved  has  been 
much  abused  by  the  indiscriminate  and  too  extensive  use  of  the  design 
known  as  the  jacket  crown. 

The  so-called  jacket  crown  is  often  a  most  use- 
33Ck(t  €rown$.  ful  style  of  construction,  but  is  particularly  so  in  the 
restoration  of  malformed  crowns  of  teeth,  as  pre- 
viously indicated  in  Fig.  29,  and  in  conditions  of  extensive  abrasion. 
As  the  proportions  of  the  remaining  natural  crown,  however,  are  ordi- 
narily retained  at  the  expense  of  the  strength  of  the  artificial  substitute, 
because  of  the  limited  amount  of  space,  the  requirements  of  occlusion  and 
alignment  must  be,  or  be  made,  favorable  to  the  reception  of  a  crown 
possessing  sufficient  strength  to  withstand  the  stress.  For  this  reason 
the  use  of  gold  in  combination  with  porcelain  facings  usually  affords 
greater  strength  than  all-porcelain  work. 

In  the  restoration  of  the  crowns  of  malformed 
malformed  Cceth.  teeth  the  use  of  the  jacket  crown  is  particularly  ap- 
plicable because  of  the  usual  favorable  shape  and 
formation  of  the  natural  crown ;  and  for  the  reason  that  it  is  often  de- 
sirable to  preserve  the  vitality  of  the  pulp  in  such  teeth,  because  of  the 
probable  unfavorable  length  and  imperfect  development  of  the  root,  which 
might  often  preclude  securing  adequate  mechanical  attachment  of  a  dowel 
■crown. 

In  such  conditions  the  destruction  of  the  natural  crown  would,  of 
course,  be  of  doubtful  advantage,  and  sometimes  even  unwarrantable ;  and 
the  preservation  of  the  vitality  of  the  pulp  presents  a  favorable  prognosis 
because  usually  so  little  mechanical  preparation  would  become  necessary 
that  no  great  shock  or  irritation  would  be  induced,  and  the  dentine  is 
not  deprived  of  the  protection  of  its  coat  of  enamel. 

This  style  of  crown  is  also  frequently  indicated 
€xtCn$iV(  Jlbrasi^n.  as  a  means  of  arresting  the  destructive  influences  of 
abrasion,  and  restoring  the  natural  crown  in  a  useful 
and  aesthetic  manner.  If  the  occlusion  in  such  cases  is,  or  may  be  made, 
favorable  for,  and  the  requirements  indicate  the  use  of,  porcelain  facings, 
the  preservation  of  the  remaining  natural  crown  may  afford  the  advantage 
of  a  more  accurate  and  perfect  reproduction  of  the  occlusal  surfaces,  and 
at  the  same  time  adequate  stability  to  the  attachment  of  the  crown. 

The  advisability  of  destroying  the  vitality  of  the  pulp  in  these  cases 
is  much  a  matter  of  judgment,  but  is  not  always  essentially  a  prophylactic 


I30 

measure,  because  such  conditions  are  not  usually  found  in  early  life- 
Hence,  as  a  result  of  the  combined  influences  of  age  and  continued  at- 
trition, the  pulps  have  usually  receded,  and  the  canals  are  not  infrequentljr 
found  to  be  partially  or  entirely  obliterated.  The  degree  of  s'ensitiveness 
manifested  during  the  necessary  mechanical  preparation  will  serve  as  a 
guide,  however,  in  indicating  the   requirements  in  this  connection. 

The  first  procedure  constitutes  the  preparation 
Procedure.  of  the   remaining  natural  crown  until  its  periphery 

presents  a  favorable  shape  for  the  accurate  adapta- 
tion of  a  band,  and  the  labial,  lingual  and  incisal  surfaces  are  sufficiently 
reduced  to  afford  accommodation  for  a  facing,  and  admit  of  a  favorable- 
occlusion.     (Fig.  115,  a.) 


A  band  of  about  30-gauge  22-karat  gold  should 
Band,  then  be  fitted  to  the  root,  passing  just  freely  beneath 

the  gum.  After  completing  the  adaptation  of  the  cer- 
vical end,  the  labial  portion  should  be  cut  away  on  a  gradual  slope,  closely 
following  this  surface  of  the  remaining  crown,  until  the  facing  may  be  car- 
ried to  the  gum  line.  The  lingual  portion  of  the  occlusal  end  should  then 
be  trimmed  until  it  ofifers  no  interference  to  the  occlusion,  after  which  the 
interior  of  the  band,  in  position  on  the  root,  should  be  filled  even  to  its 
edge  with  wax,  and  the  bite  and  impression  secured. 

When  the  model  has  been  obtained  and  mounted 
Tacing.  upon  the  articulator,  a  facing  of  the  thin  neck  va- 

riety of  mould  (Fig.  115,  b.)  should  be  selected  and 
ground  to  place,  with  a  slight  allowance  for  the  thickness  of  the  backing. 

Pure   gold,   34   to   36-gauge,   should   be   closely 
B(ICbin9.  adapted  to  the  entire  lingual  surface  of  the  facing, 

so  as  to  join  or  come  in  direct  contact  with  the  band 
along  its  labial  and  cervical  edge  when  adjusted  to  position  (Fig.  115,  c). 
When  the  backing  has  been  properly  burnished  and  trimmed,  and  anchored 
to  the  facing  by  bending  the  pins,  the  band  should  be  detached  from  the 
model,  then  replaced  in  position  and  the  proper  relation  between  it  and 
the  facing  sustained  with  adhesive  wax.    The  joint  between  the  band  and- 


'3' 

backing  should  also  be  filled  with  melted  wax  as  a  means  of  keeping  it 
clean  and  facilitating  the  subsequent  union  of  the  two  with  solder. 

\\'hen  invested,  the  wax  should  be  removed  and 

Soldering.  a  small  cap  of  22-karat  or  pure  gold  closely  fitted  to 

the  interior  edge  of  the  band.     The  case  should  now 

be  fluxed,  heated  and  soldered,  with  as  much  re-enforcement  and  contour 

as  the  occlusion  will  permit.     (Fig.   115,  d.) 

In  cases  where  a  broad,  flat  contact  surface  for  the  opposing  teeth 
may  be  required,  successive  layers  of  clasp  metal  may  be  attached  with 
solder  until  a  favorable  occlusion  is  secured.  In  this  event  the  incisal 
end  of  the  thin  pure  gold  backing  must  be  also  adequately  re-enforced 
wath  solder,  though  a  better  method  of  backing  for  such  cases  will  be 
subsequently  considered. 

It  will  be  noted  that  the  adaptation  of  the  crown  to  the  projecting 
conical  end  of  the  natural  tooth  is  not  close,  but  a  closer  conformation  is 
usually  unnecessary  if  the  cervical  edge  fits,  as  the  increased  quantity  of 
cement  thus  used  in  mounting  adds  materially  to  the  strength  of  the 
attachment. 

If,  for  any  reason,  a  more  perfect  adaptation  may  seem  indicated,  or 
desirable,  it  may  be  easily  secured  by  burnishing  or  swaging  a  cone  of 
pure  gold,  34  to  36  gauge,  or  platinum  foil,  i-iooo  in  thickness,  to  the 
tooth  in  the  mouth,  after  the  band  has  been  fitted  and  trimmed ;  then 
adjusting  first  the  cone  and  then  the  band  to  position,  removing  them 
ill  situ,  with  their  relation  sustained  wdth  wax,  and  investing  and  solder- 
ing them,  when  the  crow^n  may  be  completed  as  indicated. 

Such  a  procedure  is  seldom  required  or  even  warrantable,  how-ever, 
because  so  little  cement  could  be  used  in  mounting  that  a  more  or  less 
weak  attachment  would  necessarily  result.  While  the  simple  telescoping" 
cone  is  sometimes  used  without  the  band,  the  latter  is  essentially  advan- 
tageous as  a  means  of  securing  sufficient  strength  at  the  cervical  end 
and  adequate  adaptation  to  the  root  beneath  the  gum. 

When  the  crown  has  been  finished  and  polished,  the  remaining  natu- 
ral tooth  should  be  roughened  or  slightly  serrated  with  a  thin  edge  stone, 
or  sharp  bur,  before  mounting,  as  such  a  procedure  ofifers  a  mechanical 
supplement  to  the  adhesive  properties  of  the  cement,  which  affords  in- 
creased strength  in  the  attachment. 

Jlpplicatiott  to  Trregularities. 

The  jacket  crown  may  also  be  found  occasionally  useful  in  the  treat- 
ment of  irregularities,  where  the  character  and  position  of  the  teeth,  and 
the  age  of  the  patient,  may  not  warrant  the  usual  procedure  for  their  cor- 
rection. 


132 

The  method  advocated  by  Dr.  George  Evans  is  illustrated  in  Fig. 
1 16,  and  consists  of  constructing  a  gold  crown  for  the  malposed  tooth, 
and  then  attaching  a  facing  to  it  by  means  of  a  heavy  round  wire,  so 
adjusted  as  to  carry  the  facing  in  its  proper  relation  to  the  adjacent  teeth, 
and  to  be  free  of  the  occlusion. 

The  more  or  less  conspicuous  appearance  of  the  gold  crown,  even 


Fic].ll6. 


though  partially  hidden  by  the  facing,  is  an  objectionable  feature,  how- 
ever, and  equally  useful  and  more  artistic  results  could  be  usually  ob- 
tained by  sacrificing  the  natural  crown  and  adapting  a  dowel  crown  to 
support  the  facing  in  its  proper  position. 

Jlpplication  of  Taciiids  to  Bicuspid  €rown$. 

As  a  means  of  eliminating  the  objectionable  and  conspicuous  display 
of  gold  in  crowning  the  bicuspid^,  the  application  of  porcelain  facings  to 
gold  crowns  is  frequently  indicated,  and,  if  skilfully  executed,  approaches 
the  more  artistic  results  achieved  in  the  use  of  porcelain  work,  or  dowel 
crowns. 

While  various  methods  are  advocated  and  employed,  a  slight  modi- 
fication of  the  one  suggested  by  Dr.  Hollingsworth  meets  the  requirements 
in  the  most  practical,  artistic  and  expeditious  manner. 

In  the  procedure  the  gold  crown  should  be  first 

Procedure.  constructed  by  any  of  the  various  methods  in  which 

the   swaged  cusp   is  used,  but  the  band  and   cusps 

should  be  soldered  with  22-karat  solder,  and  no  re-enforcement  of  the 

cusp  made  at  the  time  of  uniting  it  to  the  band. 

When  thus  completed,  and  roughly  finished,  the  root  should  receive 
further  and  proper  preparation  for  the  accommodation  of  the  porcelain 
facing.  This  constitutes  sacrificing  the  buccal  surface  on  a  gradual  slope 
to  the  lingual,  at  an  angle  sufficient  to  admit  of  the  presence  of  the  facing 
when  placed  in  position  on  the  crown,  as  previously  illustrated  in  Fig.  40. 


133 

The  crown  should  now  be  adjusted  to  the  root 

Preparing  Crown      and  the  outline  of  the  exposed  area,  to  be  occupied 

for  Reception         by  the  facing,  marked  in  the  gold  with  a  sharp-pointed 

Of  Porcelain.  instrument,  and  subsequently  cut  out  with  a  fine  saw, 

as  indicated  in  Fig.  117,  a. 
After  filing  the  edge  smooth  and  even,  with  the  convex  surface  of 
a  fine  half-round  gold  file,  a  thin  cuspid  facing  of  proper  size  and  color 
should  be  selected  and  ground  to  place. 


F/a.//7. 


While  the  grinding  may  be  done  on  models, 
Hdapting  facing.  when  necessity  or  occasion  requires,  the  most  accu- 
rate results  can  be  accomplished  by  filling  the  in- 
terior with  wax,  when  in  position  on  the  root,  and  completing  the  adapta- 
tion in  the  mouth.  In  grinding  to  the  necessary  alignment,  and  approxi- 
mation with  the  edge  of  band,  care  should  be  exercised  to  avoid  sharp 
angles  and  an}^  unnecessary  weakening  of  the  pins. 

When  the  desired  adaptation  has  been  completed, 
Hdapting  Backing,  a  sufficient  allowance  for  the  thickness  of  the  backing 
should  be  made  by  further  grinding  the  facing  or 
the  band,  or  both ;  and  the  facing  then  backed  up  with  pure  gold,  about 
34  gauge.  In  the  adaptation  of  the  backing  a  small  surplus  should  be 
allowed  to  project  beyond  the  facing  at  all  points  (Fig.  117,  b),  and  care 
must  be  exercised  to  avoid  overlapping  it,  to  accomplish  which  it  may 
sometimes  be  necessary  to  cut  out  a  small  V-shaped  piece  at  each  occlusal 
angle. 

The  facing  and  backing  should  now  be  placed  in 
Soldering  Backing,  position  on  the  crown,  and  a  sharp  instrument  passed 
around  the  buccal  edge  of  the  crown,  marking  the 
proper  relation  between  it  and  the  backing  (Fig.  117,  c),  after  which  it 
should  be  detached,  and  the  backing  soldered  to  the  crown  from  the 
outside  with  20-karat  solder,  using  enough  to  form  a  smooth  joint,  which 
may  finish  down  flush  with  the  porcelain  when  the  surplus  is  removed ; 


T34 

and  the  necessary   re-inforcement   of  the  cusps   should  be  made  at  this 
time. 

The  proper  relation  between  the  parts  may  be  most  easily  and  securely 


Fiq.llB. 


sustained  while  soldering-  by  the  use  of  pliers  similar 
'in  design  to  those  previously  recommended  for  attach- 
ing cusps,  or  the  ordinary  nickel  automatic  soldering 
tweezers  may  be  used  by  bending  one  end  at  right  angles, 
as  indicated  in  Fig.  ii8. 

When  the  soldering  has  been  completed,  the  fac- 
ing should  be  adjusted  to  position  and  the  surplus 
trimmed  down  until  a  smooth  edge  presents  between 
crown  and  facing,  being  careful  to  az'oid  any  over- 
hanging  edges  of  metal  upon  porcelain. 

While  the  permanent  reten- 
SOldcring  Tacins.  tion  of  the  facing  may  be  secured 
by  bending  the  pins  down  against 
the  backing,  on  the  inside  of  the  crown,  greater 
strength  will  be  obtained  by  soldering,  on  account  of 
the  extreme  thinness  of  the  backing.  This  may  be 
quite  easily  accomplished  by  first  bending  the  pins 
down  close  upon  the  backing,  and  then  wrapping  the 
crown  with  one  thickness  of  asbestos  paper,  with  the 
occlusal  end  folded  together,  and  the  whole  held  in  place  by  wiring. 
The  backing  and  pins  should  then  be  fluxed,  preferably  with  liquid  flux, 
and  a  sufficient  quantity  of  i8-karat  solder  also  fluxed,  and  placed  in 
position.  This  should  now  be  carried  to  the  flame,  with  the  porcelain 
downward,  and  gradually  brought  to  the  point  of  greatest  heat  (Fig. 
119),  when  a  small  flame  from  the  blow-pipe  may  be  directed  upon 
the  facing  until  the  solder  fuses,  which  can  be  readily  observed  from  the 
open  cervical  end. 

While  this  or  any  other  style  of  investment  is  not  altogether  neces- 
sary, if  extreme  care  be  exercised  in  subjecting  the  crown  to  the  heat,  the 


Fiq.119. 


^35 

use  of  asbestos  paper  possesses  the  advantage  of  absorbing  but  little,  if 
-any,  heat,  and  of  precluding  the  possibility  of  fracturing  the  facing,  bv 
■distributing  it  evenly. 

When  the  soldering  has  been  completed,  the  crown  should  be  treated 
to  the  acid  bath,  and  then  finally  polished  (Fig.  117,  d),  and  mounted. 

If  an  undue  prominence  of  the  root  interferes  with  its  proper  adjust- 
ment, it  may  become  necessary  to  sacrifice  more  from  the  buccal  surface, 
but  the  lingual  surface  should  alvva}s  be  allowed  to  remain  as  long  as 
possible,  in  order  to  afford  the  greatest  degree  of  strength  to  the  at- 
tachment. 

Another  process  or  method  productive  of  prac- 
Uariation  Of  method,    tically  the  same  results,  but  entailing  a  different  pro- 
cedure, is  employed  by  many.     This  constitutes  first 
making  the  band,  and  fitting  it  to  the  root,  and  then  cutting  out  the  buccal 
surface  to  accommodate  the  facing  as  indicated  in  Fig.  120,  a. 


F/C7./20. 


The  usual  bite  and  impression  should  now  be  taken  and  the  models 
secured  and  mounted  upon  the  articulator.  A  cuspid  facing  of  suitable 
size  and  color  is  then  ground  to  place  until  the  proper  alignment,  and  a 
perfect  joint  with  the  cervical  and  approximal  edges  of  the  band,  are 
secured.  After  backing  the  facing  with  30-gauge  22-karat  gold,  and 
bending  the  pins  (Fig.  129,  b),  the  band  should  be  detached  from  the 
model,  the  facing  placed  in  position  upon  it,  and  their  relation  sustained 
with  a  nnniite  quantity  of  fluxed  wax.  Asbestos  paper  should  now  be 
wrapped  around  the  parts  and  w'^-ed,  as  indicated,  and  the  joint  between 
the  two  filled  with  20-karat  solder  (Fig.  120,  c). 

This  portion  of  the  crown  should  now  be  readjusted  to  the  models, 
and  the  cusps  formed  to  fit  the  band  and  facing,  and  meet  the  require- 
ments of  occlusion,  after  which  they  should  be  filled  with  i8-karat  solder. 

In  attaching  the  cusps  to  the  band  and  facing  they  should  be  first 
Tetaiued  in  proper  relation  by  the  use  of  a  small  quantity  of  fluxed  wax. 
Asbestos  paper  should  now  be  wrapped  around  the  crown  with  the  oc- 
clusal end  knuckled  in  close  to  the  cusps,  and  then  wired  securely  to  place 


136 

by  twisting-  the  wire  very  taut  around  the  approximal,  occlusal  and  cer- 
vical surfaces,  to  sustain  the  relation  of  the  cusps,  as  well  as  having  an  • 
additional  piece  of  wire  pass  around  the  center  of  the  crown  to  hold  the 
paper  together. 

With  the  surplus  ends  of  the  wire  projecting  from  the  cervical  end 
of  the  crown,  it  may  be  carried  to  the  flame,  cusps  dozvnward,  and  so  held 
until  the  solder,  already  in  the  cusps,  has  re-fused  and  united  with 
the  band. 

If  insufficient  solder  has  been  placed  in  the  cusps  to  accomplish  union 
in  such  manner,  more  may  be  added  at  this  time,  and,  as  in  the  previously 
mentioned  method,  if  any  danger  of  re-fusing  or  unsoldering  joints, 
already  made,  seems  probable,  the  same  can  be  overcome  and  prevented 
by  first  coating  them  with  a  solution  of  whiting  in  alcohol  or  water,  or 
other  similar  means. 

After  soldering,  the  crown  should  be  allow^ed  to  cool  slowly  and 
gradually,  and  then  may  be  removed  from  the  investment,  finished  and 
polished  (Fig.   120,  d). 

While  such  crowns  may  be  invested  in  ordinary  investment  material, 
the  soldering  can  be  accomplished  with  equal  facility  and  accuracy,  and 
much  more  easily,  in  this  manner. 

Jlpplication  of  Saadlc-back  Cectb  to  BiCHspia  and  molar  €rown$. 

The  application  of  the  saddle-back  tooth  to  the  construction  of  bi- 
cuspid and  molar  crowns  is  sometimes  practicable  as  a  means  of  admitting 
of  the  shell  or  telescope  principle  of  attachment,  and  of  affording  an  ar- 
tistic and  aesthetic  result,  because  of  presenting  an  occlusal  surface  of 
porcelain. 

The  element  of  strength  possessed  by  such  a  crown,  however,  depends 
much  upon  the  extent  of  space,  and  the  force  of  the  masticating  stress,. 
in  the  individual  case,  as  the  Ungual  cusps  are  weak  points,  unless  suf- 
ficient space  exists  so  as  to  require  but  little,  if  any,  grinding,  and  adequate 
opportunity  is  offered  for  protecting  and  supporting  them. 

In  the  procedure  incident  to  the  construction  of 
PfCCCdur^,  such  a  crown,  the  band  should  be  made  and  fitted 

in  the  same  manner  pursued  for  an  all  gold  crown, 
and  the  bite  and  impression  then  taken. 

The  root  should  be  afterward  trimmed  to  accommodate  the  presence 
of  the  porcelain. 

When  the  models  are  mounted  upon  the  articulator,  a  saddle-back 
tooth  (Fig.  121,  A),  the  occlusal  surface  of  which  approximates  the  size 
and  proportions  of  the  band,  should  be  selected.  In  no  instance  should 
the  porcelain  be  much  smaller  than  the  diameter  of  the  band,  but  in  the; 


^i7 

event  of  its  being  too  large  it  may,  of  course,  be  ground  to  proper  pro- 
portions. 

The  band  should  now  be  detached  from  the  model  and  cut  away  with 
curved-pointed  shears  to  admit  of  the  proper  adjustment  of  the  porcelain 
(Fig.  121,  b). 

The  porcelain  should  then  be  carefully  ground  until  it  meets  the  re- 
quirements of  alignment  and  occlusion,  comes  in  contact  with  the  remain- 
ing cervical  edge  of  the  band,  and  fits  into  the  interior  of  the  lingual  and 
occlusal  portion. 

It  should  now  be  backed  up  with  pure  gold,  about  34  gauge,  securelv 
attached  by  bending  the  pins  (Fig.  121,  c),  and  then  placed  in  position 
on  the  band,  and  the  proper  relation  sustained  with  melted  wax. 

After  filling  the  interior  with  soft  wax  to  keep  it  clean,  the  crown 
should  then  be  invested  by  submerging  it  in  a  slight  coverino-  of  invest- 
ment material,  leaving  only  the  wax  exposed. 


Upon  removing  the  wax  the  interior  of  the  crown  will  be  exposed, 
when  flux  can  be  applied  and  sufficient  solder  placed  over  the  pins  and 
around  the  joint.  The  case  should  then  be  gradually  heated  to  a  red 
heat,  when  a  small  flame  from  the  blow-pipe,  directed  into  the  crown,  will 
quickly  accomplish  the  soldering. 

When  removed  from  the  investment  and  subjected  to  the  acid  bath, 
the  band  should  be  burnished  up  closely  to  the  porcelain,  and  the  crown 
finished  and  polished  (Fig.  121,  d). 

In  the  application  of  crowns  constructed  by  these 
DomI$.  latter  methods,  the  shortness  of  the  root  may  some- 

times indicate  the  use  of  a  dowel  as  a  means  of 
supplementing  the  band  and  affording  a  stronger  attachment  to  the  root. 
When  this  is  required,  or  seems  desirable,  it  should  be  first  fitted  to  the 
canal  and  a  projecting  end  extended  into  the  lingual  portion  of  the  crown 
as  far  as  its  proper  adjustment  will  admit.  The  dowel  should  then  be 
cemented  to  place  in  the  root,  and  the  crown  separately  and  subsequently- 
mounted. 


tbe  Band  and  Dowel  grown. 


CHAPTER   IX. 

Indications.  Requirements:  Mechanical,  Esthetic;  Cervical  Curvature,  Alignment, 
Color  and  Harmony,  Oil  Colors,  Manufacturers'  Products.  Dental  Labora- 
tories. Method  of  Construction  :  Procedure ;  Bands,  Soldering,  Fitting.  Form- 
ing Cap.  Dovv^els.  Bite.  Impression.  Adaptation  of  Facing;  Cervical  End, 
Incisal  or  Occlusal  End.  Backing  of  Facing ;  Adaptation.  Re-enforcement. 
Soldering,  Finislung.  Variation  in  Method.  Use  of  Platinum.  Investing. 
Soldering.  Finishing.  Application  of  Partial  Bands :  Comparative  Advantages. 
Indications,  Procedure.  Application  of  Riveted  Facings :  Procedure,  Riveting. 
Application  of  Detachable  and  Replaceable  Facings:  Advantages  Claimed,  Ad- 
vantages Considered,  Advantages  Obtainable,  Various  Designs;  Mason's  Facing; 
Application.  Roach's  Facing;  Application.  Dwight's  Facing  ;  Application.  Bry- 
ant's Method  :  Applicttion  ;  Box  Method,  Tube  Method.  Davis  Crown.  Applica- 
tion to  Bicuspids  and  Molars:  Indications;  Bicuspids,  Molars.  Procedure; 
Re-enforced  Cap,  Use  of  Tvi^o  Dowels,  Bite  and  Impression.  Use  of  Flatback 
Facing,  Facing,  Cusps,  Adaptation,  Approximal  Restoration,  Investing,  Solder- 
ing. Use  of  Saddle-Back  Teeth :  Procedure.  Use  of  Vulcanite  Teeth.  Ap- 
plication of  Removable  Crowns.  Application  to  Irregularities:  Indications; 
Malposition,  Construction,  Extension  for  Support  of  Facing,  Hygienic  Con- 
siderations. Diminution  of  Normal  Space ;  Separation  of  Teeth ;  Application 
of  the  Intradental  Band :  William's  Method,  Application ;  Cigrand's  Method, 
Application.  Repairing :  Replacement  of  Facings ;  Usual  Method,  Procedure. 
Brewer's  Method;  Application.  Underwood's  and  Mitchell's  Method;  Applica- 
tion. Dwight's  Method;  Application.  Bryant's  Method;  Application.  Replac- 
ing Bicuspid  and  Molar  Facings.  Replacement  of  Facing  and  Backing;  Proce- 
dure. Removing:  Use  of  Excising  Forceps,  Separating  Cap  and  Dowel;  Ac- 
curacy in  Model  Making,  Improved  Articulators. 


The  usefulness  and  seviceability  of  the  band  and  dowel  crown  in  the 
various  phases  of  its  present  application  and  construction  account  for  its 
extensive  employment,  and  warrant  giving  special  emphasis  to  the  detail 
of  the  respective  methods  advocated. 

While  the  primitive  application  of  a  band  as  applied  particularly  to 
the  construction  of  anterior  crowns,  and  combined  with  a  dowel  and  porce- 
lain tooth  or  facing,  was  probably  first  suggested  by  Dr.  C. 
M.  Richmond,   the    present    methods    of    construction,    and    the    facil- 


139 

ities  for  accomplishing  the  requirements,  have  so  modified  the  original 
design  as  to  cause  its  complete  abandonment,  and  the  adoption  of  a  proce- 
dure more  practical,  artistic  and  expeditious. 

As  there  have  been  innumerable  processes  proposed,  onl\-  the  more 
jn-acticable  of  those  now  in  use  will  receive  attention. 

Tndications. 

Because  of  the  necessary  use  of  porcelain  for  esthetic  reasons,  and 
of  the  additional  strength  and  stability  in  the  attachment  afforded  by  the 
presence  of  a  band,  together  with  the  hermetical  sealing  of  the  root  and 
the  safeguard  against  fracture,  this  style  of  construction  is  indicated  in, 
and  universally  applicable  to,  the  restoration  of  the  ten  anterior  teeth, 
and  not  infrequently  the  first  molars.  Within  the  sphere  of  its  applica- 
tion it  occupies  the  same  degree  of  general  utility,  and  offers  the  same 
assurances  of  favorable  permanency  as  does  the  gold  crown  in  the 
restoration  of  posterior  teeth. 

As  the  application  is  confined  to  the  range  of  vision,  the  requirements 
in  connection  with  the  construction  of  such  crowns  may  be  properly  classi- 
fied as  mechanical  and  esthetic,  and  yet  in  all  efforts  calculated  to  be  pro- 
ductive of  a  high  degree  of  permanency  and  artistic  endeavor  the  two 
cannot  well  be  disassociated. 

Whilst   it   is  now   generally   conceded   that   the 

mechanical.  addition  of  a  band  to  dowel  crowns  affords  the  pre- 

viously mentioned  advantages,  it  is  also  readily 
acknowledged  that  the  mechanical  adaptation,  or  relation,  of  the  same  to 
the  end  of  the  root  must  be  uniformly  deep,  and  close  enough  to  the  per- 
iphery to  preserve  the  continuity  of  surface  between  root  and  crown  at 
the  line  of  junction  beneath  and  within  the  free  margin  of  the  gum,  so 
that  no  irritating  influence  may  result.  At  the  same  time,  it  is  almost 
equally  essential  that  the  band  should  be  sufficiently  narrow  to 
be  entirely  invisible,  and  thus  admit  of  bringing  the  porcelain  into  close 
proximity  with  the  gingival  margin ;  and  yet  strong  enough  to  retain  its 
given  shape  and  form  during  the  process  of  fitting  and  adapting,  and 
when  subsequently  subjected  to  the  stress  of  mastication. 

The  importance  of  properly  trimming  the  end  of  the  root  to  begin 
with,  has  already  been  sufficiently  emphasized,  and  is  particularly  appar- 
ent in  the  shaping  of  anterior  roots,  because  of  their  even  more  conical 
shape.  If  this  is  neglected  in  the  slightest  degree,  the  cervical  edge  of 
the  band  must  form  a  shoulder  between  it  and  the  surface  of  the  root, 
which,  though  hidden  by  the  gum,  affords  opportunity  for  the  lodgment 


140 

and  accumulation  of  food  deposits,  the  subsequent  decomposition  of  which 
is  productive  of  a  decidedly  unhygienic  condition,  and  much  consequent 
discomfort.  While  nature  may  aid  the  indifferent,  careless  or  negligent 
operator  for  a  time,  by  covering  over  the  evidences  of  such  efforts — and 
in  this  connection  the  tissues  surrounding  roots  supporting  artificial 
crowns  cover  a  multitude  of  sins — the  result  is  inevitable ;  hence,  no  band 
at  all  were  better  than  one  zvhich  does  not  fit. 

In  the  esthetic  restoration  of  the  crowns  of  ante- 
€$thCtiC$.  rior  teeth,  success,  with  all  it  implies,  is  codependent 

upon  the  ability  to  observe  the  minutest  details  in  an 
endeavor  to  simulate  nature,  and  that  degree  of  enthusiasm  and  ambition 
which  prompts  a  thorough  and  efficient  execution  of  the  artistic  require- 
ments involved. 

These  embrace  a  consideration  of  the  details  of  Cervical  Curvature, 
Alignment,  Color  and  Harmony. 

In  order  that  the  natural  cervical  curvature  of 

Cervical  Curoature.     the  gum   tissue  should    remain  normal,  and    that  no 

metal  should  be  visible  in  the  finished  crown,  it  is 

essential  that  its  adaptation  should  be  made  with  this  requirement  in  view. 


Ficj.122. 

A  common  fault  of  this  kind,  the  disregard  of  which  materially  in- 
creases the  artificial  appearance  of  the  work,  as  compared  with  the  correct 
and  artistic  outline,  is  illustrated  in  Fig.  122. 

The  feature  of  alignment  with  adjacent  teeth  is 
Jllisnmcnt.  most  important,    and  particularly    as  applied  to    the 

cervical  half  of  the  crown.  A  common  fault  with 
many  crowns,  otherwise  artistic,  is  an  undue  prominence  at  the  neck,, 
which  is  caused  by  not  cutting  the  labial  portion  of  the  root  short  enough, 
or  by  the  selection  of  a  facing  too  thick  or  bulbous  at  this  point,  and  the 
failure  to  properly  reduce  it,  by  grinding,  before  the  completion  of  the 
crown. 

A  proper  and  equally  symmetrical  alignment  of  the  incisal  end  should 
also  be  observed,  and,  while  the  occlusion  may  govern  to  some  extent,  it 
is  often  permissible  to  grind  interfering  opposing  teeth  slightly  to  admit 
of  securing  this.     In  this  connection  considerable  trimming  and  shaping 


141 

of  the  ends  and  uneven  and  irregular  edges  of  natural  teeth  may  often  be 
done  to  their  improvement  and  benefit,  and  entirely  without  harmful  or 
injurious  results,  if  done  carefully  and  judiciously,  such  surfaces  being 
afterward  polished  smooth  with  fine  disks. 

As  nothing  in  nature  is  more  apparent  than  the 
Color  and  I)armony.     universal   expressions  of  harmony,   it  is,  of  course, 
essential  in  simulating  it  that  every  effort  should  be 
expended,    and    every    facilitity    employed,    to    obtain    this    in    the    con- 
struction of  artificial  crowns,  that  they  may  more  closely  resemble  the  re- 
maining natural  teeth. 

The  selection  of  a  tooth  or  facing  of  the  proper 

Color.  color,  with  due  allowances  for  any  change  which  may 

be  occasioned  by  the  presence  of  a  metal  backing,  or 

other  means  of  diminishing  its  translucency,  is  often  a  difficult  and  very 

exacting"  problem,  and  those  who  are  so  unfortunate  as  not  to  be  endowed 

with  an  accurate  and  artistic  eye  will  often  be  seriously  handicapped. 

The  color  should  be  selected  with  these  possible  changes  in  view,  and, 
particularly  in  the  restoration  of  the  six  anterior  teeth,  should  usually 
match  the  natural  tooth  corresponding  to  the  one  being  crozvned  (if  pres- 
ent), as  a  variation  in  the  color  of  natural  teeth  in  the  same  mouth  is 
marked,  to  which  special  attention  has  been  given  in  a  splendid  contribu- 
tion by  Dr.  E.  C.  Royce,  of  Chicago.  If  some  variation  seems  unavoid- 
able, a  slightly  darker  shade  is  usually  preferable  to  a  lighter  one,  and 
efifects  a  less  conspicuous  and  in  consequence  more  artistic  result. 

The  use  of  the  high-fusing  oil  colors,  introduced 
Oil  Colors.  by   Mr.   Robert   Brewster,   of  Chicago,   or  a  lower- 

fusing  variety  made  by  C.  Ash  &  Sons,  makes  it  pos- 
sible to  obtain  almost  any  desired  variation  of  shade  in  a  single  facing,  as 
well  as  to  more  perfectly  and  artistically  imitate  the  characteristics  of  the 
remaining  natural  teeth.  These  are  prepared  in  several  basal  or  primary 
colors,  and  in  obtaining  color  and  shadow  effects  are  to  be  thinly  mixed  and 
painted  on  the  lingual  surface  of  the  facing,  immediately  after  the  grinding 
has  been  completed,  then  placed  in  the  furnace  and  fused,  after  which, 
when  the  desired  result  has  been  obtained,  the  crown  is  constructed  as 
intended. 

In  reproducing  pits,  grooves,  erosion,  tobacco  stains,  etc.,  the  colors 
are  to  be  painted  upon  the  labial  surface,  after  properly  grinding,  and  then 
fired  before  backing. 

Harmony  in  shape,  form   and   characteristics   is 
I)armony.  scarcely  second  in  importance  to  color,  and  at  least 

in  salient  features  should  be  closely  observed,  as  the 
artistic  possibilities  increase  in  proportion  thereto. 


142 

The  shape  and  general  form  of  the  porcelain  tooth  or  facing  should 
be  the  same  as  the  corresponding  natural  tooth  (if  present)  ;  the  length 
from  cervical  to  incisal  edges  should  be  the  same  as  the  adjacent  teeth; 
the  angles  and  incisal  edge  should  be  characteristic  of  the  remaining  teeth, 
and  in  the  event  of  the  presence  of  numerous  and  conspicuous  gold  fillings 
the  artificial  crown  should  be  similarly  treated. 

In  complying  with  such  requirements  too  much 
manufacturers'         should    not  be    expected  of  the    manufacturers    and 
PifOdUCfS.  supply  houses,  as  it  would  be  impossible  for  their  best 

efforts  to  be  productive  of  results  which  could  rea- 
sonably be  expected  to  be  universally  adaptable  to  all  cases.  Their  prod- 
ucts represent  only  the  efiforts  of  the  artisan  in  catering  to  the  general 
demand,  and  the  successful  operator  only  can  and  must  become  the  artist. 
A  selection  which  approaches  the  requirements  should  be  made,  and 
then  ground  and  shaped  as  the  characteristics  of  the  case  may  indicate.  In 


f/c^.  123. 

nearly  all  makes  of  porcelain  teeth  this  can  be  done  with  impunity  if  the 
surfaces  so  ground  are  afterwards  repolished  with  fine  disks,  and  the  re- 
sult is  even  more  natural  than  the  highly  glazed  surface. 

It  is  this  particular  feature  that  should  impel 
Dental  CaboratcriCS.  the  progressive,  conscientious  dentist  to  acquire  such 
skill  as  may  enable  him  to  execute  his  own  work,  for 
the  practice  of  relegating  this  class  of  work  to  dental  laboratories,  where, 
in  the  majority  of  them,  the  motto  observed  in  making  bands  is  to  have 
them  large  enough  to  admit  of  easy  and  ready  adjustment;  where  cusp- 
forms  are  made  by  the  office  boy,  by  the  score ;  where  the  color  is  but  a 
chance;  where  accompanying  instructions  that  the  bite  is  normal  will 
suffice,  and  where  time  and  revenue  are  necessarily  the  only  serious  con- 
siderations, should  be  condemned  as  materially  retarding  the  progress  and 
advancement  of  an  artistic  ,eld  of  professional  effort. 


'43 

metDoa  of  Construction. 

In  a  consideration  of  the  method  of  constructing  this  style  of  crown, 
the  consecutive  stages  of  which  are  illustrated  in  Fig.  123,  sjxjcial  empha- 
sis must  again  he  given  to  the  essentials  of  root  preparation,  and  particu- 
larly to  the  feature  of  allowing  the  end  to  project  about  one-sixteenth  of 
an  inch  from  the  gum  until  the  peripheral  trimming  has  been  accom- 
plished, the  measurement  taken,  and  the  band  fitted. 

The  importance  of  this  procedure  has  already  been  sufficiently  empha- 
sized, and  cannot  be  overestimated,  as  a  neglect  to  observe  or  a  disregard 
of  it  will  adfl  materially  to  the  difficulties  encountered,  and  to  the  degree 
of  inaccuracy  and  discomfiture  resulting. 


f/(7./24. 


When   the    remaining   natural    crown   has   been 
Procedure.  cut  to  the  desired  extent,    and    the    projecting    end 

of   the     root   properly    trimmed,    the    measurement 
should  be  taken  in  the  manner  already  indicated. 

A  band  should  now  be  cut  the  exact  length  of 

Bands.  the  measurement,  about  one-eighth  of  an  inch  wide, 

and  of  22  karat  gold,  28  or  29  gauge  in  thickness. 

The  edges  should  be  filed  straight  and  smooth, 

Soldering.  and  the  band  annealed  and  made  into  circular  form. 

By  first  overlapping  and  then  abutting  the  ends,  their 

contact  may  be  sustained  when  heated,  as  already  described,  and  the  joint 

should  be  soldered    from  the  inside  with  a    minute  bit  of  22   or  20  karat 

solder. 

The  first  procedure  incident  to  fitting  the  band 

fitting.  should  be  to  give  it  a  general  shape  approximating 

that  of  the  root,  and  then  to  trim  the  cervical  edge  to 

closely  follow  the  curvature  of  the  gum,  with  the  joint  at  the  center  of  the 

lingual  surface.     Curved  pointed  plate  shears,  or  the  crown  shears  espe- 


144 

cially  designed  for  such  trimming  (Fig.  124)  may  be  used  for  this 
pVirpose. 

When  thus  trimmed  so  as  to  come  in  uniform  contact  with  the  gum 
when  loosely  and  temporarily  adjusted  to  the  end  of  the  root,  the  edge 
should  be  filed  smooth  with  the  convev  surface  of  a  fine  half-round  file 
(Grobet,  4  to  5  inch,  No.  5),  and  then  nicely  rounded,  always  avoiding  a 
thin  feather-edge  for  the  reasons  mentioned. 

The  band  should  now  be  placed  upon  the  projecting  end  of  the  root, 
and  then  forced  gently  to  position  with  a  small  piece  of  wood,  until  it 
passes  just  freely  beneath  the  gum.     (Fig.  125,  A.) 

While  the  topical  application  of  solutions  of  cocaine,  carbolic  acid, 
etc.,  are  frequently  relied  upon  as  a  means  of  obtunding  the  pain,  the  use 
of  any  therapeutic  agent  is  seldom  necessary  where  the  band  fits  a  pro- 
jecting end  of  a  properly  prepared  root,  as  this  serves  to  first  conform  it  to 


ncf.125. 

the  proper  shape,  and  then  guide  it  to  place,  thus  causing  little,  if  any,  dis- 
comfort, A  very  great  percentage  of  cases  where  any  acute  pain  is  occa- 
sioned can  usually  be  attributed  to  forcing  the  band  into  the  tissue,  instead 
of  its  closely  following  the  outlines  of  the  root,  and  passing  under  and 
within  the  free  margin  of  the  gum,  without  unnecessarily  impinging  upon 
the  periosteum  or  peridental  membrane. 

When  the  cervical  end  has  been  properly  adapted,  the  band  should  be 
removed  and  trimmed  until  the  labial  surface  is  as  narroiv  as  pos- 
sible to  meet  the  requirements,  but  gradually  sloping  until  it  is  somewhat 
wider  upon  the  lingual. 

It  should  now  be  readjusted  to  the  root  and  forced  well  to  place  until 
it  is  Entirely  invisible  from  the  labial  aspect.  The  root  should  then  be 
ground  down  until  its  basal  surface  follows  the  outlines  indicated  and 
approximates  the  edge  of  the  band.      (Fig.  125,  B.) 


145 

While  this  relation  may  be  obtained  by  grinding  the  root  down  with 
the  band  in  position,  it  is  usually  best  to  remove  the  band  during  the  pro- 
cedure, for  the  reason  that  it  may  become  loosened  from  the  vibration,  and 
slip  downward  unobserved,  thus  endangering  the  distortion  of  its  shape ; 
or,  of  being  ground  too  narrow  to  be  useful ;  and  the  heat  produced  by 
the  friction  is  also  an  objection  to  grinding  and  shaping  a  band  in  the 
mouth. 

When  thus  properly  trimmed,  it  should  be  removed  with  a  small  hook- 
instrument,  and  the  floor  then  attached. 

The  floor  to  the  band,  in  the  attachment  of  which 

Tormins  Cap.  the  cap  is  formed,  should  be  thiji  enough  to  be  easily 

adapted  to  contact  with  the  edge  of  the  band,  and 
admit  of  bringing  the  neck  of  the  porcelain  facing  into  close  proximitv 
with  the  gum. 


Ficj.126. 


For  this  purpose,  platinum,  about  34  gauge,  is  preferable,  as  afford- 
ing the  desired  thinness  without  danger  of  being  fused  in  the  subsequent 
final  soldering  of  the  parts ;  although  pure  gold,  or  even  gold  of  22  karat, 
of  the  same  gauge,  may  be  used. 

Any  special  degree  of  strength  in  the  floor  itself  becomes  unnecessary 
ui  gold  z^'oi'k,  because  of  the  quantity  of  solder  which  will  be  subse- 
quently used  in  uniting  cap  and  facing,  and  properly  contouring  the  lin- 
gual surface. 

In  soldering  the  floor  to  the  band,  a  liberal  surplus  of  the  metal  (gold 
or  platinum)  should  be  used,  and  will  facilitate  the  procedure.  The  band 
should  be  placed  in  the  center  of  this,  without  any  special  effort  to  secure 
a  perfect  adaptation  at  this  time,  the  parts  then  fluxed  and  attached  at  one 
point  of   contact  by  the  partial   fusion  of  a  small   bit  of  20  karat    solder 


146 

placed  outside  of  the  band.  This  will  anneal  the  floor  metal  so  that  it  may 
readily  be  burnished  to  a  perfect  contact  with  the  edge  of  the  band ;  and 
absolute  contact  around  the  entire  circumference  is  essential,  as  an  opening 
or  space  filled  only  with  solder  may  be  again  opened  by  the  re-fusing  of 
the  solder  in  the  final  assemblage  of  the  crown.  In  securing  this  contact, 
however,  care  should  be  exercised  to  prevent  changing  the  shape  and  form, 
of  the  band. 

After  applying  flnx,  one  corner  of  the  floor  should  be  grasped  with 
fine-pointed  soldering  pliers,  and  again  carried  to  the  flame,  until  the  com- 
plete fusion  of  the  solder  formerly  used  unites  the'  parts  around  the 
entire  joint.  (Fig.  126.)  It  will  seldom  be  found  necessary  to  make  a 
second  application  of  solder,  for  the  quantity  required,  where  good  contact 
exists,  is  almost  infinitesimal. 

After  the  soldering  has  been  completed,  the  surplus  of  floor  metal 
should  be  trimmed  close  to  the  band,  and  the  joint  then  finished  down 
smooth,  with  stones  and  disks. 

When  adjusted  to  position  on  the  root,  the  cap  should  rest  firmly  upon 
its  seat,  and  any  tendency  to  rock  should  be  relieved.  Rocking  usually 
indicates  a  high  point  on  the  extreme  approximal  edge,  the  removal  of 
which  will  overcome  the  difficulty. 

Dowels. 

The  cap  should  now  be  removed,  and  the  canal  prepared  for  the  re- 
ception of  the  dowel,  the  requirements  of  which  have  been  already  out- 
lined. 

As  the  dowel  assumes  the  greater  portion  of  the  strain  to  which  the 
crown  will  be  subjected,  the  alloy  of  platinum  and  iridium  is  generally 
used,  because  of  its  toughness  and  strength;  and  the  round,  square  and 
triangular  wire,  in  sizes  varying  from  14  to  18  gauge,  according  to  that 
indicated  by  the  proportions  of  the  root,  are  prepared  for  the  purpose. 

The  so-called  "platinoid"  and  other  German  silver  alloys  are  also 
prepared  and  used  for  this  purpose,  but  the  only  advantage  possessed  by 
them  is  that  of  economy,  and  this  is  gained  at  the  expense  of  stiffness,, 
strength  and  permanent  integrity. 

If  there  is  any  preference  as  to  the  form  of  wire  used,  it  is  in  favor  of 
the  round,  because  of  its  being  easier  to  remove  from  the  canal  after 
mounting,  in  case  of  necessity ;  and  of  its  being  perhaps  also  easier  to  per- 
forate the  floor  of  the  cap  in  such  manner  as  to  secure  a  close  contact 
between  it  and  the  dowel  at  the  line  of  junction,  which  facilitates  and  adds 
strength  to  their  union,  and  prevents  the  solder  from  flowing  in  upon  the 
under  side  of  the  cap.  For  this  reason,  should  a  square  dowels  seem 
desirable,  round  wire,  of  heavier  gauge  may  be  used,  and  that  part  which 


H7 

enters  the  canal  filed  square  after  fitlin<>-  to  the  hole  in  the  Hoor  hut  hefore 
soldering. 

The  advantages  claimed  for  the  square  and  triangular  forms  are  that 
a  wire  drawn  with  sharp  angles  possesses  greater  strength  and  resistance 
than  a  round  one ;  and  that  any  possihle  rotation  of  the  crown  on  conical 
roots,  after  mounting,  is  precluded.  If  the  wire  used  is  of  adequate  size  to 
meet  the  requirements,  the  round  form  possesses  sufficient  strength,  how- 
ever, and  there  can  he  no  rotation,  if  the  crown  is  well  adapted  and  the 
mounting  is  secure. 

•  In  fitting  to  the  canal  a  length  should  be  cut  which  will  afford  some 
surplus,  and  one  end  then  slightly  tapered.  When  thr  dowel  has  been 
properly  prepared  and  adapted,  the  cap  should  be  placed  in  position  and 
a  large  round  or  oval  burnisher  used  to  outline  the  opening  of  the  canal, 
in  the  floor.  A  small  perforation  through  the  center  of  this  outline  should 
now  be  made  with  a  sharp  pointed  instrument,  or  bur,  and  the  dowel  then 
grasped  -firmly  with  pliers  and  the  tapered  end  forced  through  the  floor 
and  into  the  canal  until  in  proper  position,  which  insures  a  close  contact 
between  dowel  and  floor. 


When  properly  adjusted,  the  relation  should  be  at  once  permanently 
sustained  by  soldering,  to  accomplish  which  base-plate  gutta  percha,  tem- 
porary stopping,  or  adhesive  wax,  should  be  warmed  and  packed  around 
the  projecting  end  of  the  dowel,  and  over  the  surface  of  the  cap.  WHien 
this  is  cool,  which  may  be  hastened  by  a  spray  of  cold  water,  they  should 
be  carefully  detached  from  the  root,  and  the  interior  of  the  cap  filled  with 
plaster  or  investment  material,  until  the  dowel  is  covered.  (Fig.  127.) 
The  use  of  any  more  investment  material  than  absolutely  necessary  only 
adds  to  the  difficulty  of  soldering,  and  it  is  essential  that  it  should  be 
packed  down  into  the  cap  well  to  prevent  burning  the  band.  After  this 
investment  has  crystallized,  the  removal  of  the  temporary  medium,  by 
warming  over  the  flame,  will  admit  of  securely  attaching  the  parts  with 
solder  by  the  use  of  the  small  mouth  blowpipe. 

In  the  event  of  accidentally  making  too  large  a  perforation  through 
the  floor,  an  additional  piece  of  the  metal  of  smaller  dimensions  may  be 
properly  perforated  and  burnished  down  over  the  surface  before  removing 


148 

and  investing  the  cap  and  dowel,  and  subsequently  attached  at  the  time  of 
soldering. 

The  cap  should  be  cleaned  in. the  acid  bath  after  removing  from  the 
investment,  and  then  adjusted  to  position  on  the  root  and  the  bite  and 
impression  taken. 

In  the  construction  of  anterior  crowns,  the  tak- 

"BltC."  ing  of  a  "bite"  usually  becomes  necessary  only,  when 

some  abnormality  of  occlusion,  or  irregularity  of  the 

opposing  teeth,  presents.     Otherwise  the  lingual  contour  of  the  adjacent 

teeth  as  represented  in  the  model  will  indicate  the  outlines  to  be  followed 

by  this  portion  of  the  crown. 

When  a  bite  is  necessary,  it  should  be  taken  in  wax,  preceding  the 
impression,  and  should  be  secured  in  accordance  with  the  requirements  of 
the  impression,  and  in  the  manner  previously  outlined. 

The  impression  should  then  be  taken  in  plaster 

Tmprcssion.  for  the  reasons  already  stated,  and  should  always  in- 

clude teeth  on  each  side  of  the  one  being  crowned, 
and  the  corresponding  toothy  when  present. 

If  the  projecting  surplus  end  of  the  dowel  is  slightly  bent,  the  cap 
will  be  removed  with  the  impression,  but  in  the  event  of  its  remaining  upon 
the  root,  it  should  be  detached  and  adjusted  accurately  to  position,  and 
securely  sustained,  if  necessary,  with  a  little  melted  wax.  The  interior  of 
the  cap  and  the  surface  of  the  dovel  should  now  he  covered  with  a  slight 
film  of  melted  zvax  to  facilitate  and  admit  of  its  ready  removal  from  the 
model,  and  the  impression  then  varnished  and  filled. 

When  the  model  has  been  obtained,  the  bite,  if  one  has  been  taken, 
should  be  adjusted,  and  the  case  mounted  upon  the  articulator.  The  cap 
may  now  be  easily  detached  by  grasping  the  end  of  the  dowel  with  pliers, 
and  the  wax  then  removed  from  its  interior,  which  will  admit  of  its  ready 
and  accurate  readjustment,  thus  facilitating  the  investment  of  the  crown, 
and  permitting  the  preservation  of  the  model. 

In  cases  where  the  remaining  natural  teeth  are  quite  loose,  or  support 
artificial  crowns  of  doubtful  stability,  the  use  of  small  particles  of  wax 
packed  into  the  interproximal  spaces,  and  into  all  undercuts,  will  be  found 
to  be  advantageous  to  the  removal  of  the  impression,  and  to  the  comfort 
of  the  patient. 

Jldaptation  of  Tacinds. 

Previous  to  the  selection  and  adaptation  of  the  facing,  the  surplus  end 
of  the  dowel  should  be  cut  ofif  with  excising  forceps  or  cutting  pliers,  leav- 
ing it  as  long  as  possible  so  as  not  to  interfere  with  the  adjustment  of  the 
facing  to  its  proper  position. 


149 

As  the  floor  is  very  thin,  however,  some  Httle  surplus  should  always 
be  allowed  to  remain,  in  order  to  add  strength  to  the  attachment  of  the 
dowel. 

A  long  pin  facing  should  now  be  selected  and  ground  to  a  perfect 
joint  with  the  cap,  along  its  cervical  curvature,  and  then  to  meet  the 
requirements  of  length,  contact  and  characteristics. 

When  this  required  and  proper  adaptation  of  the 

Cerokal  end,         cervical  end,  to  the  cap,  is  secured,  the  inner  surface 

of  the  facing  should  be  thinned  down  somewhat  until 

sufficient  space  exists  to  afford  opportunity  for  securing  a  close   joint 

between  the  backing  and  the  cap,  with  solder. 


Ficj.l26 


The  incisal  or  occlusal  end  should  now  be  bev- 
eled about  half-way  to  the  pins,  in  order  that  it  may 
present  a  smooth,  sharp  angle,  instead  of  the  usual 
rounding  edge.      (Fig.    128.)      This  becomes  neces- 
sary as  a  means  of  affording  a  definite  edge  to  which  the  backing  may  be 
subsequently  finished. 


Tnclsal  or 
Occlusal  end. 


The  use  of  the  clamp  designed  by  Dr.  A.  Brom  Allen,  of  Chicago 
(Fig.  129)  will  be  found  convenient  for  holding  porcelain  facings  while 
grinding. 

BacRitid  of  Tactiid. 

The  backing  of  porcelain  facings  becomes  necessary  in  metal  work 
as  a  means  of  supporting  them,  by  affording  a  surface  which  will  admit  of 
their  subsequent  attachment  with  solder. 

The  requirements  in  this  connection  embrace  two  essential  features : 
First,  the  backing  must  be  closely  adapted  to  the  porcelain,  and,  second,  it 
must  be  sufficiently  strong,  rigid  and  unyielding,  to  protect  the  porcelain 
from  the  strain  of  mastication 

While  numerous  methods  are  employed,  the  following  will  be  found 


ISO 

to  be  productive  of  the  most  certain  and  accurate  results,  though  possibly 
somewhat  less  expeditious  than  the  more  simple  methods  usually  observed. 

Pure  gold,  about  34  gauge,  cut  somewhat  larger  than  the  facing,  and 
to  extend  from  cervical  to  incisal  or  occlusal  edges,  should  be  perforated 
for  the  ready  reception  of  the  pins,  annealed,  and  carefully  burnished  to 
a  perfect  adaptation. 

As  it  is  desirable  that  the  perforations  should  be  properly  placed,  so 
as  to  admit  of  the  free  and  easy  adjustment  of  the  porcelain  to  position, 
and  to  preclude  any  strain  upon  the  pins  in  adapting  the  backing,  it  should 
first  be  observed  that  the  pins  are  straight  and  parallel  with  each  other,  and 
that  this  surface  of  the  porcelain  is  clean  and  free  of  wax. 

As  a  means  of  ascertaining  the  exact  position  of 

Adaptation.  the  pins,  the  gold  should  be  laid  on  a  smooth  surface 

and  the    facing  placed    over  it,  pins    downward,  and 

sufficient  pressure  applied  with  the  thumb  to  make  a  slight  indentation. 


Ficj.130. 

Or,  a  thin  film  of  melted  wax  may  be  previously  placed  on  the  surface  to 
facilitate  this,  though  this  is  unnecessary  because  of  the  softness  and 
thinness  of  the  pure  gold. 

The  perforations  may  now  be  made  with  a  punch  designed  for  the 
purpose,  or  with  a  sharp  pointed  instrument  of  proper  size.  The  use  of 
the  latter  possesses  the  advantage  of  throwing  up  a  small  furrow  of  metal 
around  the  holes,  and  is  preferable. 

After  annealing  and  burnishing  the  gold  to  a  perfect  adaptation,  the 
surplus  should  be  trimmed  away  to  closely  follow  the  porcelain  on  all  sur- 
faces except  the  incisal  or  occlusal,  where  a  slight  projecting  edge  should 
be  allowed  to  remain. 

While  the  requirement  of  adaptation  has  now  been  complied  with  in 
the  best  and  easiest  possible  manner,  that  of  strength  is  yet  to  be  observed. 

As  the  strain  upon  a  facing  is  generally  applied 
Rt-cnf  orcein  cut.  directly  upon  the  end,  and  then  diverted  to  the  point 
of  resistance  afforded  by  the  pins,  it  is  necessary  that 
a  uniform  re-enforcement  extending  over  this  area  should  be  made. 

To  best  obtain  this,  and  thus  combine  the  requirements  of  adaptation 
and  strength,  a  second  piece  of  gold,  preferably  about  22  karat,  29  or  30 


i'^l 


■gauge,  slioLild  be  perforated,  hurnished  to  place,  and  trimmed  to  extend 
from  the  pins  to  the  incisal  or  occlusal  end  only,  with  a  corresponding  sur- 
plus at  the  latter  point. 

The  two  backings  should  now  be  adjusted  to  po- 
Solderlnfl.  sition  on  the  facing  and  reburnished,  then  removed, 

placed  together  with  the  holes  approximating  each 
other,  which  is  facilitated  by  the  furrow  of  metal  produced  by  being 
punched  with  a  sharp  instrument,  and  theq  attached  with  20  or  18  karat 
solder.  Small  pieces  of  the  latter  should  be  consecutively  applied  to  the 
joint  between  the  two,  presenting  toward  the  cervical  end,  until  the  inter- 
vening space  is  completely  filled,  which  may  be  easil}-  and  quickly  accom- 
plished by  grasping  the  backings  with  the  soldering  pliers,  as  indicated  in 
Fig-  I30>  the  use  of  which  securely  sustains  their  relation,  and  precludes 
any  distortion  of  shape. 

The  use  of  an  excess  of  flux  should  be  avoided,  and  care  must  be  ex- 
ercised to  prevent  the  solder  from  filling  the  perforations,  or  flowin<y 
through  to  the  under  side  of  the  backing,  and  thus  destroying  the  adapta"^ 
tion.  The  latter  may  be  easily  avoided  by  coating  this  surface  with  a  solu- 
tion of  whiting,  but  is  usually  prevented  by  the  upturned  edges  surround- 


ing the  perforations,  which  also  generally  precludes  their  filling  up  with 
solder.  The  use  of  small  pieces  of  graphite  from  an  ordinary  lead  pencil, 
trimmed  to  snugly  fit,  and  to  project  slightly  from  each  side,  will  also 
overcome  any  such  tendency. 

When  the  soldering  has  been  completed,  the  backing  should  be 
cleaned  in  acid,  adju=,ued  to  position  on  the  facing  (Fig.  131,  A),  and  se- 
curely retained  by  bending  the  pins  down  close  upon  it,  as  indicated  in 
Fig.  131,  B.  Care  must  be  exercised  in  bending  the  pins  to  catch  them 
with  pliers  at  the  extreme  end,  in  order  to  avoid  any  stress  or  tension 
which  might  result  in  immediate  or  subsequent  fracture  of  the  porcelain. 

In  finishing,  the  gold  should  be  trimmed  down  to 
TInlsblng.  close  contact  with  the  porcelain  around  all  surfaces. 

This  should  be  started  with  a  fine  file,  always  carry- 
ing it  tozvard  the  porcelain;  and  completed  with  disks,  to  insure  the  re- 


152 

moval  of  all  overhanging  edges,  the  presence  of  which  will  invariably 
cause  fractures  of  the  porcelain  along  the  edges,  due  to  the  impingement 
afforded  by  the  shrinkage  and  contraction  of  the  metal  after  soldering. 

In  trimming  away  the  surplus  from  the  incisal  or  occlusal  portion  the 
file  should  be  held  on  a  parallel  line  with  the  labial  or  buccal  aspect  of  the 
facing.  This  leaves  the  backing  its  full  thickness  along  this  edge,  the  vul- 
nerable point,  when  it  may  be  afterward  rounded  nicely  until  practically 
invisible,  and  yet  always  remain  sufficiently  long  and  strong  to  afford 
ample  protection  to  the  porcelain.  (Fig.  131,  C.)  Much  of  the  artistic 
effect  of  the  finished  crown  will  depend  upon  obtaining  and  preserving 
a  perfect  joint  between  the  neck  of  the  facing  and  the  cap,  and  while  it 
is  the  usual  practice  to  grind  this  portion  of  the  facing  thin,  and  allow 
the  backing  to  extend  entirely  over  it,  forming  a  joint  with  the  cap  which 
is  subsequently  filled  with  solder,  the  best  results  may  be  secured  by 
filing  or  grinding  away  this  edge  of  the  backing  until  the  edge  of  the 
facing  nuiy  be  placed  in  direct  contact  zvith  the  cap. 

This  admits  of  bringing  the  facing  into  closer  proximity  with  the 
gum  and  of  securing  a  better  and  more  perfect  joint  between  backing  and 
cap,  because  of  the  difficulty  and  uncertainty  usually  experienced  in 
successfully  filling  this  space  with  solder. 

The  use  of  the  clamp  previously  mentioned  may  also  be  found  ser- 
viceable as  a  means  of  holding  the  facing  while  finishing  the  backing. 

As  the  double  backing  may  seem  unnecessarily 
Uariation  In  UlCtftOfl.    difficult  or  circuitous,  various  other  methods  are  em- 
ployed in  preference,  but  probably  with  results  less 
certain  and  accurate. 

The  re-enforcement  of  the  single  pure  gold  backing  may  be  done  with 
a  lower  grade  of  gold,  or  with  solder  alone,  either  preceding  its  final 
adaptation  to  the  porcelain,  or  at  the  time  of  soldering  the  facing  to  the 
cap.  There  is  no  objection  to  this,  procedure  if  adequate  re-enforcement 
is  secured,  but  as  gold  or  solder  in  fusing  flows  to  a  thin  edge,  the  edges  of 
the  backing  and  particularly  the  incisal  or  occlusal,  where  strength  is  de- 
manded, are  quite  naturally  the  thinnest,  and  consequently  the  weakest 
portions. 

This  may  be  overcome  somewhat  by  allowing  a  slight  surplus  to  ex- 
tend beyond  the  porcelain,  especially  upon  the  incisal  or  occlusal  end,  until 
after  re-enforcing,  and  then  adjusting  to  position  on  the  facing,  and  se- 
curely attaching  and  finishing,  as  indicated.  In  no  event,  however,  when 
a  single  pure  gold  backing  is  used,  is  it  advisable  to  defer  the  re-enforce- 
ment until  the  final  soldering  of  the  crown. 

Where  a  single  backing  seems  indicated  or  desirable,  it  should  be 
made  of  22  karat  gold,  about  28  or  30  gauge,  but  as  the  burnishing  to  the 


153 

poraelain  is  thus  made  more  difficult,  the  additional  stiffness  and  strength 
is  usually  obtained  at  the  expense  of  the  adaptation. 

The  adaptation  of  heavy  single  backings  may  be  materially  improved 
by  swaging.  For  this  purpose  a  mould  of  the  lingual  surface  of  the  porce- 
lain should  be  secured  in  mouldine,  and  fusible  alloy  dies  obtained,  and 
dies  made  of  ordinary  sealing  wax,  or  hard  modeling  compound  are  also 
sometimes  used.  This  consumes  even  more  time,  however,  than  the  adapta- 
tion of  the  double  backing,  and  the  results  are  less  accurate. 

As  porcelain  facings  are  more  or  less  transparent. 
Use  Of  Platinum.       the  presence  of  a  gold  backing  is  frequently  objec- 
tionable in  the  blue  and  lighter  shades,  because  of  the 
yellowish  cast  imparted  to  them ;  hence  the  placing  of  a  surface  of  plati- 
num next  to  the  facing  is  sometimes  indicated  as  a  means  of  preserving 
the  original  color,  or  of  effecting  the  least,  or  most  desirable,  change  in  it. 

For  this  purpose,  platinised  gold  is  employed,  and  possesses  the  ad- 
vantage of  affording  a  surface  of  either  gold  or  platinum,  as  the  case  may 
require.    A  more  convenient  method,  however,  is  to  back  up  the  facing  in 


the  usual  manner,  and  then  insert  a  piece  of  platinum  foil  (i-iooo)  over 
the  desired  area  between  facing  and  backing,  just  previous  to  permanently 
attaching  them  by  bending  the  pins,  and  finishing  the  backing  to  its  proper 
adaptation ;  by  which  means  equally  good  and  perhaps  quicker  results  may 
be  obtained. 

When  the  adaptation  and  finishing  of  the  back- 
Tnoesting.  ing  have   been  completed,  the   facing  should  be  ad- 

justed to  position  on  the  cap,  and  the  proper  relation 
sustained  with  wax.  The  crown  should  now  be  removed  from  the  model, 
and  the  joint  between  cap  and  backing  well  filled  with  melted  wax.  This 
keeps  it  clean  and  free  of  investment  material,  which  is  essential  to 
securing  a  smooth  flush  joint  with  solder,  and  the  latter  may  be  facilitated 
by  using  fluxed  wax. 

Investment  material  should  now  be  mixed  to  a  thin  plastic  consist- 
ency, and  a  sufficient  quantity  poured  upon  the  surface  of  a  clean  piece  of 
paper.     The  interior  of  the  cap  should  first  be  thoroughly  filled,  and  the 


154 

crown  then  gently  forced  into  the  investment,  until  only  the  wax  remains 
exposed.  After  hardening,  the  surplus  sliould  be  trimmed  to  the  outlines 
indicated  in  Fig.  26,  and  the  wax  carefully  removed  with  a  small  pointed 
knife-blade,  being  particular  not  to  loosen  the  facing  in  its  matrix. 

In  those  cases  where  the  backing  has  been  allowed  to  extend  en^tirely 
through  between  facing  and  cap  some  difficulty  is  occasionally  experienced 
in  getting  the  solder  to  flow  nicely  into  the  joint,  and  while  this  may  usu- 
ally be  accomplished  by  properly  fluxing  and  heating  the  case  before  at- 
tempting to  solder,  if  the  proximity  of  the  surfaces  is  very  close  the  same 
may  be  greatly  facilitated  by  placing  a  small  projecting  bead  of  wax 
around  the  immediate  outside  of  the  joint,  before  investing  (Fig.  132,  A). 
When  melted  and  subsequently  absorbed  and  burned  out,  this  leaves  a 
small- space  into  which  the  heat  becomes  concentrated,  during  the  process 
of  soldering,  and  this  aids  materiall}-  in  drawing  the  solder  toward  that 
po-int. 

The  cutting  of  a  small  opening  through  the  under  surface  of  the  in- 
vesfepient  until  the  joint  is  exposed  is  also  recommended  for  this  purpose, 
and  the  same  may  be  easily  obtained  by  extending  the  bead  of  wax  previ- 
ously mentioned  until  it  is  of  proportions  sufficient  to  leave  such  an  open- 
ing after  its  removal.      (Fig.  132,  B.) 

In  cases  where  two  or  more  individual  crowns,  approximating  each 
other,  are  being  constructed  at  the  same  time,  they  should  always  be  in- 
vested separately,  as  it  is  often  quite  difficult  to  solder  them,  when  con- 
tained in  the  same  investment,  without  attaching  them  together. 

Previous  to  heating  the  case  for  the  purpose  of 
Soldering.  final   soldering,   and   after  the   investment  has  been 

properly  trimmed,  and  all  debris  removed,  liquid  flux 
should  be  applied  to  the  surface  of  cap  and  backing,  and  worked  well  down 
into  the  joint.  If  the  latter  is  done  after  the  case  is  heated,  or  if  powdered 
flux  is  used,  its  penetration  to  the  full  depth  of  the  joint  is  made  more 
doubtful. 

The  case  should  now  be  placed  over  the  flame  and  gradually  heated 
■until  red;  when  medium-sized  pieces  of  solder,  previously  fluxed,  should 
l)e  separately  and  consecutively  applied,  and  fused,  until  the  joint  is  first 
jfilled,  and  the  desired  contour  obtains.  If  the  case  is  properly  heated,  this 
can  be  easily  and  readily  accomplished  with  a  small  pointed  flame  from  the 
blowpipe. 

When  the  soldering  has  been  completed,  the  crown  should  be  allowed 
to  cool  slowly  by  gradually  diminishing  the  size  of  the  flame  under  it,  until 
it  may  be  turned  off  entirely.  Many  prefer  to  place  the  work  in  a  cooling 
oven,  or  to  submerge  it  into  dry  plaster  until  cold,  but  either  procedure  is 
entirely  unnecessary. 


155 

After  cooling  sufficient!)-,  it  should  be  removed 
Tinishind.  from  the    investment,  treated    to  the  acid    bath,  and 

then  finished  with  stones  and  disks  in  the  engine,  and 
subsequently  polished  on  the  lathe,  when  it  is  ready  for  mounting. 

Jipplicatioti  or  Partial  Bands. 

The  application  of  a  partial  band  encircling  only  the  approximal  and 
lingual  surfaces  of  the  root  is  advocated  and  employed  more  or  less 
frequently  in  the  construction  of  dowel  crowns,  as  a  means  of  avoiding 
the  presence  of  a  labial  band,  from  an  esthetic  standpoint,  and  of  pre- 
cluding its  possible  irritating  influence,  as  a  prophylactic  measure. 

A  consideration  of  the  comparative  advantages 

Comparative  leads   to  the  conclusion  that_,  while  a  band  encom- 

JldvantagCS.  passing    the    entire    circumference    doubtless    adds 

greater  stability  to  the  attachment  of  the  crown, 
affords  a  more  perfectly  hermetical  sealing  of  the  end  of  the  root,  over- 
comes the  possibility  of  fracture,  may  be  made  practically  invisible,  and 
will  not  necessarily  prove  a  source  of  irritation,  providing  that  it  fits,  the 
partial  band,  if  well  adapted  to  the  lingual  and  approximal  surfaces, 
fortifies  the  attachment  against  stress  in  the  direction  from  which  stress 
is  exerted,  makes  it  possible  to  bring  the  facing  into  absolute  and  direct 
contact  with  the  tissue,  and  precludes  any  irritation  at  this  point,  or  the 
conspicuous  and  objectionable  appearance  of  the  band  in  the  event  of 
subsequent  recession  of  the  tissue. 

The  indications  for  the  application  of  this  mode 

Indications,  of  construction  are  more  or  less  general,  but  depend 

much  upon  personal  experience  and  preference,  com- 
bined with  a  careful  observation  of  the  particular  requirements  of  the 
case  tinder  treatment. 

Of  special  indications,  the  most  favorable  are  those  cases  where  the 
root  is  sufficiently  strong  to  insure  permanent  support  to  a  crown ;  or 
where  the  labial  portion  of  the  root  may  have '  been  destroyed  to  the 
border  of  the  alveolus ;  where  the  extreme  shortness  of  the  crown,  or 
the  thinness  and  transparency  of  the  tissue  surrounding  the  root,  would 
likely  show  the  presence  of  the  band;  where  recession  of  the  gums  has 
exposed  the  labial  portion  of  the  root ;  and  where  pathological  conditions 
alreadv  exist,  or  the  tissue  may  seem  to  be  particularly  susceptible 
to  any  possible  irritating  influence. 

Procedure. 

While  several  methods  of  securing  the  desired  adaptation  are  em- 
ployed, the  most  positive  and  accurate  results  may  be  obtained  by  fol- 


iS6 


lowing  the  same  detail  of  procedure  indicated  for  a  circular  band,  up  to 
and  including  its  fitting,  shaping  and  trimming,  as  previously  outlined. 

When  the  band  has  been  thus  fitted  and  trimmed,  a  floor  of  platinum- 
or  pure  gold,  about  34  gauge,  should  be  first  simply  attached  to  the  lingual 
surface  by  the  partial  fusion  of  a  small  piece  of  solder.  The  floor  should 
then  be  adapted  closely  to  the  entire  edge  of  the  band,  and  a  precaution- 
ary measure  observed  to  prevent  their  union  with  solder  along  that  edge 
of  the  band  which  is  to  be  subsequently  cut  away.  To  accomplish  this, 
such  portion  of  the  joint  between  floor  and  band  should  be  filled  with  a 
solution  of  whiting,  or  occupied  by  a  thin  piece  of  mica  (Fig.  133  A) 
and  the  soldering  completed  around  the  approximal  and  lingual  sur- 
faces. 

The  surplus  floor  metal  should  be  trimmed  off  on  a  line  with  the- 
band,  and  the  labial  portion  of  the  latter  cut  away  to  the  desired  point 
with  curved  shears,  always  leaving  the  edge  nicely  rounded.  (Fig.. 
133  B.) 


a 


Fiq,l33. 


When  the  trimming  and  finishing  of  the  cap  have  been  completed,  it 
should  be  adjusted  to  position  on  the  root,  and  the  projecting  labial  portion 
of  the  floor  burnished  to  a  close  adaptation  to  the  surface  and  to  the  per- 
ipheral outline. 

The  dowel  should  be  fitted  and  subsequently  soldered,  and  the  impres- 
sion then  taken,  and  the  crown  completed  as  already  outlined.       (Fig. 

133  C.) 

A  method  wherein  only  a  partial  or  semi-circular  band  is  fitted  to 
the  root  instead  of  a  circular  one,  and  where  the  floor  is  then  attached 
and  adapted  by  burnishing,  is  sometimes  employed,  but  while  this  requires 
less  time,  the  adaptation  is  also  less  accurate. 


Jlpplicaticn  of  Rii^eted  Tacinds. 

Because  of  the  apparent  dread  exhibited  by  those  of  limited  con- 
fidence or  experience,  towards  the  process  of  soldering  anything  necessarily 
involving  porcelain,  for  fear  of  checking  it,  and  of  its  possible  change  of 
color  as  a  result  of  the  application  of  heat,  a  method  has  been  devised- 


157 

whereby  the  occurrence  of  either  or  both  of  these  objectionable  features 
might  be  entirely  and  positively  eliminated. 

The  process  defers  the  permanent  attachment  of  the  facing  to  the 
backing  until  after  the  construction  and  assemblage  of  all  the  metal  parts 
of  the  crown,  after  which  it  is  then  securely  anchored  by  riveting  the  pins. 

While  there  are  probably  no  particular  objections  to  this  method, 
except  that  the  facing  is  held  less  rigidly,  there  are  no  special  advantages 
apparent  because  of  the  limited  possibilities  of  checking  facings,  which 
have  been  previously  mentioned  in  connection  with  "Soldering,"  and  of 
the  fallacy  of  a  probable  change  in  color  resulting  from  the  heat  of 
soldering. 

That  any  perceptible  change  of  color  is  due  mainly  to  the  presence 
of  the  backing,  and  not  to  the  heat,  is  proven  in  porcelain  work,  where, 
when  necessarily  subjected  to  a  very  much  higher  degree,  it  is  even  then 
the  rare  and  exceptional   occurrence ;   and  it   would   also   seem  that  the 


Ficj,l34- 

impact  and  vibration  produced  by  subsequently  riveting  the  projecting 
ends  of  the  pins  down  close  upon  the  backing  would  be  equally  as  "haz- 
ardous" a  process  as  that  of  soldering. 


Procedure. 

In  the  construction  of  crowns  by  this  method  the  same  general 
details  as  previously  outlined  are  observed  up  to  and  including  the  adap- 
tation of  the  backing. 

When  this  has  been  accomplished  it  should  be  adjusted  to  position  on 
the  facing  and  finished  down  as  desired,  in  the  usual  manner,  except 
that  the  pins  are  not  bent  to  sustain  the  relation  of  the  two  during  the 
process. 

Facing  and  backing  together  are  placed  in  proper  relation  to  the 
cap  and  sealed  with  a  small  quantity  of  hard  or  adhesive  wax  in  such 
manner  as  to  securely  attach  the  backing,  but  to  allow  the  projecting  ends 
of  the  pins  to  remain  freely  exposed.     (Fig.  134  A.) 


158 

The  crown  should  now  be  gently  removed  from  the  model  and  the 
facing  carefully  detached  from  the  backing. 

Small  pieces  of  graphite  trimmed  from  a  lead  pencil  are  then  closely 
fitted  into  the  holes  in  the  backing  and  allowed  to  project  far  enough  on 
each  side  to  be  securely  held  by  the  investment,  and  to  admit  of  properly 
forming  the  lingual  contour  with  solder  without  being  covered  over. 
(Fig.  134  B.) 

The  remaining  incisal  portion  of  the  lingual  surface  of  the  backing 
should  be  covered  with  wax  to  keep  it  clean,  and  the  crown  invested. 
Upon  the  subsequent  removal  of  the  wax  the  parts  should  be  freely 
exposed,  fluxed,  heated  and  soldered  as  usual,  being  careful  to  note  that 
the  ends  of  the  graphite  pins  are  not  covered,  and  that  the  solder  does  not 
penetrate  to  the  under  surface  of  the  backing,  which  is  prevented  by 
painting  around  the  pins  with  whiting. 


/^/,y./3J. 


When  the  soldering  has  been  completed,  the  graphite  may  be  broken 
off  even  with  the  surfaces  and  removed  from  the  holes  by  the  use  of  a 
sharp  pointed  instrument  or  bur  of  the  same  diameter. 

The  facing  should  now  be  adjusted  to  position  and  the  lingual  surface 
of  the  crown  trimmed  to  allow  a  free  exposure  of  the  projecting  ends  of 
the  pins.  The  holes  should  then  be  slightly  countersunk  with  a  round  bur, 
the  crown  roughly  finished  with  stones  and  disks,  and  the  facing  finally 
adjusted  for  riveting. 

As  a  means  of  facilitating  the  process  of  riveting, 
RiPCtlng.  and  of  lessening  the  liability  of  fracturing  the  porce- 

lain, the  riveting  forceps  designed  by  Dr.  Frank  A. 
Brewer,  St.,  may  be  used  to  advantage;  or  the  crown  may  be  invested, 
facing  downward,  in  a  base  of  plaster  about  an  inch  in  depth  (Fig.  135) 
and  the  riveting  hammer  used.     In  the  latter  method  the  projecting  ends 


159 

of  the  pins  are  flattened  flown  over  the  backing  sc-jjaratelv, 
with  moderate  and  well-directed  blows  from  a  small  ri\'etin}^  hammer.  If 
the  crown  is  properly  invested,  with  a  sufficient  depth  of  plaster  beneath 
and  supporting  the  facing,  and  the  whole  rests  upon  a  firm  seating,  this 
may  be  done  wdthout  danger  of  fracturing  the  porcelain.  The  riveted  ends 
are  then  smoothed  down  with  disks  and  the  crown  finished  and  polished, 
l)urnishing  the  metal  up  close  to  the  porcelain  around  ihe  edges. 

Jlpplicdtion  of  Detachable  and  Replaceable  Tacin^s. 

The  not  infrequent  presentation  of  broken  facings  resulting  after  the 
permanent  mounting  of  the  crown,  combined  with  the  more  or  less  diffi- 
cult operation  of  replacing  them  in  a  secure  and  artistic  manner,  lias 
resulted  in  the  introduction  of  various  means  for  overcoming  the  former 
and  simplifying  the  latter. 

Several  varieties  of  detachable  and  replaceable  facings  are  designed 
for  this  purpose,  and  are  applicable  to  the  construction  of  dowel  crownis 
as  well  as  bridgework,  though  perhaps  more  generally  so  to  the  latter. 

While,  as  a  usual  thing,  it  must  be  granted  that  the  subsequent  frac- 
turing of  a  porcelain  facing  is  due  to  one  of  two  causes,  i.  e.,  either  faulty 
adaptation  of  the  backing,  wdierein  it  afifords  insufficient  strength  or 
inadequate  protection,  or  a  total  disregard  of  the  requirements  of  occlusion, 
the  use  of  a  style  which  is  easily  replaceable  is  doubtless  an  advantage  in 
some  instances. 

When  these  common  faults  in  regard  to  backing  the  facings  are  com- 
bined with  the  severe  strain  to  which  the  porcelain  is  often  subjected  in 
some  conditions  of  occlusion,  and  the  perhaps  unnecessarily  rough  usage 
sometimes  unconsciously  accorded  them,  any  practical  means  of  facilitating^ 
repair  in  the  event  of  accident  is  materially  useful.  .    .  ,j. 

The  advantages  claimed  by  the  advocates  of  this- 
Hdoantaacs  Claimed,  style  of  facing  are:  First,  that  the  porcelain  is  not 
subjected  to  the  heat  of  soldering;  second:  facings^ 
may  be  more  easily  replaced  in  the  event  of  becoming  fractured;  thircfr 
the  probability  of  becoming  fractured  from  usage  is  greatly  diminshed 
because  the  facing  is  not  so  rigidly  attached  to  the  metal  backing;  fourth, 
the  color  is  not  changed. 

The  first  point  made  is  practically  the  zveakest, 
JIdPantases  Considered,  because  the  fracturing  of  a  facing  during  the  process 
of  soldering  it  to  any  kind  of  an  attachment  is  inex- 
cusable, and  can  be  invariably  attributed  to  either  a  lack  of  skill  or  a 
neglect  of  detail. 

The  second  must  be  regarded  as  problematical,  at  least  in  the  manner 


i6o 

in  which  these  facings  are  ordinarily  used,  for  the  reason  that  it  is  often 
impossible  to  properly  adapt  any  style  or  kind  of  facing  to  the  individual 
case  without  considerable  grinding. 

For  this  reason  also  the  subsequent  replacement  of  even  an  exact 
duplicate  of  the  same  mould  would  occasion  the  necessity  for  grinding 
the  latter  to .  an.  accurate  fit  and  adaptation  with  the  stationary  backing, 
and  to  meet  the  esthetic  requirements,  which,  irrespective  of  the  manner 
of  attachment,  is  not  usually  an  easy  or  simple  procedure. 

The  third  feature  presents  the  most  practical  and  plausible  advantage, 
Ijecause  a  porcelain  facing  supported  by  mechanical  means  supplemented 
with  an  intervening  medium  such  as  gutta  percha,  or  even  cement,  which 
a€ords  a  somewhat  cushion-like  effect,  will  withstand  greater  stress  than 
one  held  firm  and  rigid.  Hence  fracture  is,  of  course,  less  likely  to  occur 
since'the- facing  willyield  slightly  to  stress  before  breaking. 

The  fourth  point  of  advantage  is  doubtful,  for  the  reason  that  any 
change  of  color  is  usually  due  to  excessive  heat,  or  the  presence  of  the 
backing,  as  has  been  previously  mentioned. 

■'  :   ■  >•       If  the  highest  advantages  are  to  be  obtained  ini 

•  ■  TldVinttagCS  the  use  of  this  style  of  porcelain  facing,  the  adoption 

'"'Obtainable.  of  a  method  suggested  and  practiced  by  Dr.  F.  T. 

Van  Woert  and  others  will  be  found  most  practicable. 

This  consists  of  properly  grinding  and  adapting  two  or  more  facings 
of  the  same  color  and  mould,  as  the  conditions  of  occlusion  may  seem  to 
indicate,  for  each  case  at  the  time  of  construction.  Those  not  used  in 
completing  the  crown  are  then  placed  in  small  boxes  or  other  convenient 
receptacles  and  labeled  with  the  patient's  name.  In  case  of  breakage  occur- 
ring at  any  subsequent  time,  a  duplicate  requiring  no  fitting  or  grinding, 
and  which  may  be  readily  adjusted  to  position,  is  conveniently  obtainable. 

While  such  a  procedure  may  involve  considerably  more  work  at  the 
time,  much  may  often  be  saved  in  the  long  run,  and  particularly  in  difficult 
cases,  where  much  grinding  is  necessary. 

Uarious  Designs. 

Of  the  various  designs  of  detachable  facings  now  procurable,  the 
demand  has  seemingly  not  justified  the  adoption  of  any  one  special  make 
in  preference  to  the  others,  nor  their  extensive  manufacture  in  any  great 
variety  of  moulds  and  colors. 

The  design  of  removable  or  detachable  facing 

mason's  Tacind.       devised  by  Dr.  W.  L.  Mason,  of  Red  Bank,  N.  Y.,  is 

probably  the  most  extensively  used.     It  consists  of 

a  heavy  gold  backing  having  a  triangular  slot  through  the  center  and  a 

tacing.with  a  projecting  corresponding  triangular  platinum  bar  extending 


i6i 

longitudinally,  through  tlie  center,  which  readily  telescopes  into  the  slot 
in  the  hacking.     (Fig.  136  A.) 

These  facings  are  oljtainahlc  in  a  fairly  good  variety  of  moulds  and 
colors,  and  the  principle  of  attachment  is  secure  and  admits  of  easy  adjust- 
ment. The  objectionahle  features  lie  in  the  seemingly  excessive  proportion 
of  platinum  baked  in  the  porcelain,  which  floubtless  weakens  the  latter  by 
<lividing  it  through  the  center,  and  in  the  necessary  thickness  at  the  incisal 
or  occlusal  end. 

In  the  application  of  this  style  of  facing  the  cap 
Application.  should  be  completed  as  prescribed,  and  the  models 

obtained  and  mounted  upon  the  articulator.  After  the 
selection  of  the  facing  its  backing  should  Ije  adjusted  and  two  facings,  in 
situ,  ground  to  fit  the  cap  and  to  conform  to  the  usual  requirements.  When 
the  desired  adaptation  is  secured  the  relation  to  the  cap  should  be  sustained 
by  attaching  the  backing  to  it  with  hard  or  adhesive  wax,  and  the  facing 
-then  detached,  which  is  facilitated  by  a  projecting  end  of  the  platinum  bar 


DD 


^f./3e. 


at  the  incisal  or  occlusal  edge.  Care  should  be  exercised  in  securing  a 
close  relation  between  the  backing  and  the  cap,  in  order  that  any  penetra- 
tion of  solder  through  the  joint  may  be  precluded,  and  this  may  be  further 
prevented  by  filling  the  slot  and  coating  backing  with  whiting.  The 
•metal  parts  should  now  be  invested  and  soldered,  with  due  attention  to 
the  desired  lingual  contour. 

After  soldering,  the  crown  should  be  finished  (Fig.  136  B),  and  the 
facing  then  adjusted  to  position.  The  projecting  end  of  the  platinum  bar 
should  now  be  cut  off  and  the  facing  attached  to  the  backing  with  a  thick 
solution  of  gutta  percha  in  chloroform,  after  which  the  edge  should 
-be  finished  up  close  to  the  porcelain,  and  the  crown  mounted.  Or,  if 
desirable,  the  setting  of  the  facing  may  be  made  after  the  crown  has  been 
attached  to  the  root  and  cement  is  also  some  times  used. 

A  recent  design  of  removable  facing  has  been 
Koacb'S  Tacina.        devised  by  Dr.  F.  E.  Roach,  of  Chicago,  and  for  sim- 
plicity and  strength,  combined  with  accuracy  of  adap- 
tation, and  ready  application  to  either  individual  crowns  or  dummies  tor 


1 62 

bridgework,  it  presents  many  favorable  features.  The  design  consists  of 
a  facing  with  a  dovetail  lug  extending  lingualh',  which  is  stamped  of  one 
piece  of  iridio-platinum  (Fig.  137  A),  and  a  backing  with  a  slotted 
diaphragm  into  which  the  lug  fits  accurately  (Fig.  137  B). 

The  lug  is  placed  vertically  m  the  body  of  the  facing,  and,  being 
entirely  surrounded  by  porcelain,  affords  to  the  latter  a  maximum  degree 
of  strength,  and  is  set  at  an  angle  which  admits  of  easy  adjustment  to  the 
backing. 

The  hacking  is  composed  of  two  parts  securely  united.  The  outer 
portion,  which  is  of  pure  gold,  about  34  gauge,  is  intended  to  facilitate 
ready  and  accurate  adaptation  to  the  porcelain,  after  grinding;  and  the 
central  portion,  which  affords  the  means  of  attachment,  is  in  the  form 
of  a  slotted  diaphragm,  made  of  26  gauge  clasp  metal. 

While  the  principle  of  attachment  is  good  and  secure,  the  pliability 
of  the  outer  backing  insures  a  close  adaptation  to  the  surface  and  edges 
of  the  porcelain ;  the  gingival  extension  admits  of  a  close  joint  between 


FicjJ37, 


facing  and  cap,  and  no  excess  metal  exists  at  the  incisal  end  to  offer 
obstruction  to  the  occlusion,  the  merits  and  demerits  of  these  facings, 
and  their  possibilities,  range  of  usefulness  and  general  application  are 
at  present  uncertain,  because  of  the  limited  supply  and  selection  procurable. 

After  constructing  the  cap  and  obtaining  models, 

npplicaticn.  the  facing  should  be  selected  and  ground  to  place, 

closely  following  the  method  previously  outlined  with 
regard  to  the  cervical  and  incisal  preparation.  The  backing  should  then 
be  adjusted  to  place  on  the  facing  and  burnished  to  a  close  adaptation 
with  the  porcelain,  after  trimming  away  all  unnecessary  surplus  around 
the  edges. 

The  two  should  then  be  placed  in  position  on  the  cap  and  the  relation 
sustained  with  hard  wax  (Fig.  137  C),  the  facing  removed  and  the  metal 
parts  invested  and  soldered  (Fig.  137  D). 

After  finishing  the  crown  the  facing  should  be  attached  with  cement, 
or  gutta  percha,  and  the  crown  mounted.    Because  of  the  extreme  thinness 


i63 


an4  pliability  of  the  backing  surrounding  the  attachment,  this  style  of 
facing  is  also  applicable  to  the  construction  of  the  sheU  or  telescope  crown 
with  porcelain  facing,  and  to  bicuspid  and  anterior  dummies  for 
bridgework. 

Another  design  has  recently  been  devised  by  Dr. 

DwIgbt'S  Tacinfl.       W.  H.  Dwight,  of  Le  Mars,  Iowa.    This  consists  of 

a  facing  containing  a  countersunk  platinum  socket, 

which  engages  the  arms  of  a  bifurcated  spring  post,  with  threaded  shank, 

which  is  to  be  previously  attached  to  the  backing  (Fig.  138  A). 

In  the  application  of  this  principle  the  cap  should 
Jlt),pliC<ltion.  be  constructed  as  indicated,  and  the  models  secured. 

The  facing  should  then  be  selected  and  ground  to  place 
with  the  incisal  end  properly  beveled  to  afford  protection.  By  heating  the 
facing  and  pressing  its  labial  or  buccal  surface  against  a  small  piece  of 
ordinary  sealing  wax  it  may  be  conveniently  handled  during  the  process 
of  adaptation. 


When  the  grinding  has  been  completed  the  spring  post  should  be 
inserted  in  the  socket  of  the  facing  and  the  end  of  its  projecting  shank 
imprinted  in  the  surface  of  a  piece  of  pure  gold,  about  34  gauge,  to 
denote  the  location  of  a  perforation  for  it5  reception. 

The  perforation  should  then  be  made  with  a  punch  or  small  sharp- 
pointed  instrument,  and  the  projecting  threaded  shank  screwed  into  it 
until  the  backing  approximates  the  shoulder  of  the  post.  This  may  be 
facilitated  by  leaving  the  facing  attached  or  by  the  use  of  a  wrench 
designed  for  the  purpose.  The  facing  should  then  be  removed  (Fig. 
138  B),  and  post  and  backiUfg  permanently  attached  by  the  use  of  a  small 
quantity  of  solder  fused  around  the  line  of  junction  upon  the  surface  to 
be  placed  nest  to  the  porcelain,  in  order  to  stiffen  and  strengthen 
their  union. 

The  facing  is  now  replaced  and  the  backing  burnished  and  trimmed 
to  a  proper  adaptation  with  the  porcelain  and  then  placed  in  position  on 
the  cap  and  the  relation  sustained  witlj  hard  wax. 


164 

After  removing  the  porcelain  the  inner  surface  of  the  backing  should 
be  coated  with  a  solution  of  whiting  and  the  parts  invested,  soldered  and 
finished  (Fig.  138  C).  In  permanently  attaching  the  facing  to  the  crown 
the  arms  of  the  post  should  be  expanded  until  it  becomes  necessary  to  use 
some  little  pressure  in  forcing  it  to  place,  as  they  are  purposely  left 
slightly  contracted,  in  order  to  admit  of  easy  adjustment  during  the 
process  of  adaptation. 

The  facing  should  then  be  cemented  to  place  and  the  crown  polished 
and  mounted. 

The  same  principle  is  also  applicable  to  the  replacement  of  broken 
facings  on  crowns  otherwise  constructed,  and  will  receive  subsequent 
consideration  in  that  connection. 

While  the  details  are  expeditious  and  simple,  the  principle  involved 
in  this  style  of  attachment  seems  weak,  from  the  fact  that  the  mechanical 
fixation  is  insecure,  and  depends  much  upon  the  presence  of  cement  for 
the  necessary  strength. 

The  method  of  constructing  a  replaceable  facing, 

Bryant's  IllCtftOd.      devised  and  practiced  by  Dr.  Emory  A.  Bryant,  of 

Washington,  D.  C,  consists  of  forming  a  box  for 

the  accommodation  of  the  pins   as  a  portion    of    the    backing,    and    is 

applicable  to  any  size  of  the  ordinary  cross-pin  flat-back  facings,  and  to 

the  construction  of  bridgework  as  well  as  single  crowns. 

In   the    application   of  this    method   the   facing 

Application.  should   be   selected  and   ground   to  the  proper  and 

desired  adaptation,  after  which  it  should  be  backed 
with  pure  gold  or  platinum  (34  to  36  gauge),  as  the  requirements  of 
construction  may  indicate. 

In  the  box  method  a  pair  of  Barnard's  parallel 

Box  ntctbod.  pliers,  modified  by  the  addition  of  a  set  screw  and 

by  grinding  down  the  ends  of  the  beaks  to  approxi- 
mate the  diameter  of  the  pins  of  the  facing,  as  indicated  in  Fig.  139,  are 
now  accurately  adjusted  to  the  relation  of  the  pins,  and  a  strip  of  platinum, 
36  gauge,  somewhat  wider  than  the  length  of  the  pins,  is  then  wrapped 
around  the  points  of  the  pliers,  forming  a  box  for  the  reception  of  the 
pins. 

After  soldering  the  joint,  backing  and  box  are  adjusted  to  position 
on  the  facing,  and  their  relation  marked  with  a  sharp-pointed  instrument, 
after  which  they  are  removed  and  attached  by  soldering.  The  two  per- 
forations for  the  pins  should  now  be  extended  into  one  by  cutting  out 
the  metal  between  them  with  a  fissure  bur  of  about  the  same  diam- 
eter (Fig.  140  A). 

This  should  then  be  readjusted  to  position  on  the  facing,  and  the  inner 


i65 


edge  of  the  box,  and  the  ends  of  the  pins  trimmed  to  approximate,  and 
until  the  projection  offers  no  obstruction  to  the  desired  contour  or  occlu- 
sion. A  cover  of  22  karat  gold,  about  28  gauge,  somewhat  larger  than 
the  box,  is  soldered  to  this  edge  from  the  outside,  and  subsequently 
trimmed  until  all  surplus  is  removed,  which  completes  the  construction 
of  the  backing.     (Fig.  140  B.) 

The  facing  should  be  prepared  by  slightly  serrating  the  surfaces 
of  the  pins  which  present  toward  each  other,  and  then  filling  the  space 
between  them  with  soft  solder,  using  enough  to  fill  it  at  least  equal  to 
the  length  and  thickness  of  the  pins. 

This  may  be  easily  done  by  first  fluxing  the 
pins  with  soft  solder  flux,  placing  the  soft  solder 
or  fusible  alloy  in  position,  and  carefully  direct- 
ing the  flame  upon  the  porcelain,  until  it  takes 
hold  of  the  pins,  after  which  it  should  be  quickly 
plunged  into  cold  water  to  preclude  an  expan- 
sion of  the  pins,  which  might  cause  fracture  of 
the  porcelain.  Or  the  facing  may  be  placed  on 
a  charcoal  block  or  asbestos  pad,  pins  upward, 


BqJ^O 


and  the  solder  fused  by  carefully  directing  a  small  flame  upon  the 
porcelain. 

This  extension  of  soft  solder  should  be  filed  down  even  with  the 
pins  on  all  surfaces  (Fig.  140  C),  except  that  the  extreme  end  should 
remain  a  shade  heavier  or  thicker,  to  facilitate  the  subsequent  attachment 
to  the  backing  with  cement. 

Facing  and  backing  should  be  adjusted,  placed  in  proper  relation 
with  the  cap  and  temporarily  attached  with  hard  wax.  The  facing  should 
then  be  removed  and  the  box  filled  with  moistened  whiting,  and  a  staple 
of  German  silver  or  iron  wire  inserted,  with  the  ends  projecting  about 
one-quarter  of  an  inch.  This  prevents  the  solder  from  penetrating  the 
interior  of  the  box,  and  precludes  any  change  in  the  relation  of  box  and 
backing  during  the  process  of  soldering.  The  parts  should  be  invested, 
soldered  and  finished  as  usual  and  the  facing  then  mounted  with 
cement. 


i66 

A  similar  method  involves  tlie  like  adaptation  of 

Cube  Illi^tbOd',         a  separate  tithe  to  each  individual  pin,  but  as  this 

entails  much  more  work,  possesses  less  strength  and 

affords  less  opportunities  for  replacing  the  facing  in  case  of  accident,  it 

has  been  almost  entirely  superseded  by  the  former  procedure. 

The  merit  possessed  by  these  methods  lies  in  the  facility  with  which 
a  replaceable  facing  and  its  attachment  may  be  constructed,  and  the  main 
advantage  in  their  use  may  be  attributed  to  the  fact  that  the  facing  is  not 
held  so  unyieldingly  rigid  as  if  soldered. 

Among  other  advantages  possessed  by  the  Davis 
Davis  0fOWtt$.        crown  is  also  that  of  being  easily  replaceable  in  case 
of  breakage,  but  as  this  style  of  crown  in  the  various 
phases  of  its  application  will  receive  due  and  separate  consideration,  fur- 
ther reference  to  it  in  this  connection  wdll  be  deferred. 

Jfpplication  to  Bicuspids  and  molars. 

The  band  and  dowel  style  of  construction  is  applicable  to  the  restora- 
tion of  the  crowns  of  bicuspids  and  molars  as  well  as  to  the  anterior  teeth, 
but  is  more  generally  indicated  and  more  extensively  employed  upon 
bicuspids  than  upon  molars. 

While  it  is  especially  indicated  in  porcelain  work, 
Indications.  wdiere  the  root  is  necessarily  and  purposely  trimmed 

to  approximate  the  gingival  line,  it  is  also  indicated  in 
combination  with  gold,  in  order  that  the  work  may  more  closely  approach 
the  highest  esthetic  requirements.  In  this  connection,  and  in  the  absence 
of  facilities  for  doing  porcelain  work,  a  facing,  or  saddleback  or  rubber 
tooth  may  be  used  with  artistic  results,  and  particularly  where  the  short- 
ness of  the  root  demands  the  employment  of  a  dowel  attachment,  in  prefer- 
ence to  restoring  its  coronal  proportions  with  amalgam,  and  using  a  shell 
or  telescope  crown. 

The  application  is  more  generally  indicated  and 
Bicuspids.  more    practical    on    the    bicuspids,    because    of    the 

necessity  for  observing  higher  artistic  possibilities, 
and  of  the  objection  to  placing  gold  crowns  upon  these  teeth. 

In  the  restoration  of  molars,  however,  the  indica- 
ntOlars.  tions  are  not  so  general,  and  the  range  of  application 

is  more  limited,  for  the  reasons  that  such  crowns  are 
usually  beyond  the  range  of  vision,  at  least  to  an  extent  which  greatly 
diminishes  the  esthetic  requirements;  that  they  are  subjected  to  more 
vigorous  strain  in  the  act  of  mastication,  and  that  a  telescope  attachment 
to  a  projecting  end  of  the  root  doubtless  affords  greater  strength  and 


i67 

more  permanent  stability  than  is  usually  obtained  by  cutting  the 
remaining  root  down  to  the  gingival  line  and  using  a  dowel  attachment. 

It  is  claimed  by  some,  however,  that  the  preparation  of  a  short  root 
and  the  subsequent  adaptation  of  a  narrow  band,  with  accuracy,  is  so 
facilitated  as  to  present  advantageous  features,  as  compared  with  the  more 
extensive  preparation  of  the  remaining  coronal  proportions  of  the  root  for 
the  shell  or  telescope  crown. 

Yet  such  a  claim  .  everts  to  the  manner  of  the  execution  of  the  neces- 
sary details,  and  as  they  must  be  carefully  and  skilfully  observed  in  either 
instance,  the  advantage  seems  more  hypothetical  than  practical,  and  the 
judicious  preservation  of  tooth  structure  combined  with  the  stability  of 
attachment  as  applied  particularly  to  the  molar  teeth,  for  the  reasons 
mentioned,  should  precede  a  consideration  of  facility  and  possible  advan- 
tages in  the  construction. 


Procedure. 

In  the  construction  of  this  style  of  crown,  in  combination  with  gold, 
two  more  or  less  practicable  methods  are  employed,  and  they  differ  only 
in  the  style  of  porcelain  facing  or  tooth  used.  The  cap  should  be  com- 
pleted as  though  for  an  anterior  crown,  as  described,  and  the  dowel  fitted 
and  soldered. 

Where  a  heavier  and  stronger  cap  than  will  be 
Rccnforced  Cap.  afforded  by  the  thickness  of  the  band  is  indicated  or 
desirable,  the  same  may  be  obtained  by  allowing  the 
floor  to  extend  or  project  about  Vg,  of  an  inch  from  the  band,  and  then 
filling  in  until  flush  and  smooth  with  22  or  20  karat  solder.  This  will 
result  in  a  cap  possessing  good  adaptation,  a  maximum  degree  of  strength 
and  a  minimum  tendency  to  cause  irritation,  such  as  is  frequently 
indicated  in  the  restoration  of  bicuspid  crowns. 

If  the  use  of  two  dowels  should  become  necessary 
Use  Of  two  Dowels,  to  insure  sufficient  stability,  care  should  be  observed 
to  have  them  inserted  at  such  an  angle  as  to  pass  into 
the  root  readily,  and  yet  project  through  the  floor  of  the  cap  at  a  point 
at  which  they  will  offer  little,  if  any,  obstruction  to  the  proper  adjustment 
of  the  facing.  While  the  surplus  ends  may  be  cut  away  reasonably  close 
to  the  floor  after  soldering,  the  longer  they  may  be  allowed  to  remain  the 
greater  the  strength  of  their  attachment  to  the  crown. 

The  bite  and  impression  should   follow   in  the 
BffC  and  TmprcssiOtt;     "sual  manner,  and  the  models  then  be  obtained  and 
mounted  upon  the  articulator. 


i68 

Use  of  Tlat-Back  Taciitd. 

The  method  perhaps  most  usually  employed  involves  the  use  of  a 
flat-back  facing  and  gold  cusps,  and  while  this  style  of  construction  pos- 
sesses the  advantage  of  strength,  it  also  presents  the  objectionable  feature 
of  the  presence  of  an  occlusal  surface  of  gold. 

The  facing  should  be  selected  and   ground  to 
Taciltfl.  position  on  the  cap,  and  the  occlusal  end  then  ground 

to  allow  for  the  presence  of  the  cusp,  and  properly 
beveled,  as  indicated.  It  should  then  be  backed  up  with  a  single  backing 
of  pure  gold,  about  34  gauge,  which  should  be  closely  finished  down  to  the 
edges  at  all  points,  except  on  the  occlusal,  where  a  slight  projecting  surplus 
should  remain. 

Facing  and  backing  should  now  be  placed  in 
0U$P$.  position  on   the   cap   and   sustained  with  hard  wax 

(Fig.  141  A),  while  the  cusps  are  being  formed  and 
fitted  by  whatever  method  selected. 


These  may  be  accurately  obtained  by  allowing  one  or  both  of  the  pins 
to  project  away  from  the  backing,  pouring  soft  plaster  into  the  space 
and  up  against  them,  and  closing  the  articulator,  and  then  subsequently 
carving  them  and  securing  dies  in  the  manner  already  outlined.  The  pins 
are  allowed  to  project  as  a  means  of  securely  sustaining  the  plaster  during 
the  process.  Or  the  cusps  may  be  obtained  from  any  of  the  die  and  die- 
plate  systems. 

After  swaging,  the  buccal  portion  of  the  gold 
Hdaptation.  should  be  cut  away  to  the  occlusal  angle  on  a  plane 

which  will  admit  of  approximating  it  with  the  edge 
of  the  facing  and  backing.  This  will  leave  only  the  thicknesses  of  the 
gold  forming  the  cusp  and  the  backing  along  the  occlusal  edge,  but  the 
same  will  afford  ample  protection  to  the  porcelain,  and  admits  of  a  more 
esthetic  result. 

After  thus  trimming  the  cusp  to  adaptation  with  the  porcelain  the 
two  should  be  adjusted  to  the  cap  with  wax  and  adapted  to  the  articula- 
tion and  occlusion.     (Fig.  141  B.) 


169 

While  all  soldering  may  be  done  at  the  time  of  uniting  cusp,  facing 
and  cap,  it  is  usually  best  to  remove  the  cusp  and  facing  in  their  proper 
relation,  and  previously  invest  and  attach  them  with  a  sufficient  quantity 
of  20  karat  solder  to  efifect  union  and  fill  the  lingual  portion  of  the  cusps. 

To  preclude  the  checking  of  the  facing  along  the  edge,  as  a  result  of 
the  impingement  of  the  cusps  occasioned  by  the  shrinkage  of  the  solder, 
a  slight  space  should  be  allowed  between  the  backing  and  cusps,  and  this 
filled  with  wax  to  prevent  the  investment  material  from  running  in. 

When  the  parts  are  securely  sustained  with  wax 
Ht)PfOXiftial  KWtorallon.  enough  should  be  further  added  to  form  the  proper 
approximal  contour  to  secure  a  restoration  of  contact, 
and  a  small  piece  of  pure  gold,  about  36  gauge,  should  then  be  adapted 
or  burnished  to  each  approximal  side  of  the  crown,  extending  from  cusp 
to  cap,  and  held  in  place  with  the  wax.  This  forms  a  matrix  which  facili- 
tates soldering  and  gives  the  desired  approximal  contour,  but  should  not 
extend  over  the  lingual  portion  of  the  wax,  as  the  solder  must  be  subse- 
quently added  from  this  point. 

Foil  gold.  No.  60  or  120,  may  also  be  used  for  the  same  purpose,  if 
desired. 

The   crown    should   be    invested   with    a   slight 

Tnocstitig.  covering  over  and  up  to  the  edges  of  the  pure  gold 

matrices  to  hold  them  in  place,  but  with  the  lingual 

surface  freely  exposed.    When  the  investment  has  been  properly  trimmed, 

the  wax  should  be  carefully  picked  out  and  the  remainder  removed  by 

pouring  boiling  water  upon  it,  and  the  parts  then  fluxed  and  heated. 

The  soldering  should  be  done  by  the  consecutive 
Soldering.  application  of  small  pieces  of  18  karat  solder,  of  a  size 

suitable  to  be  readily  dropped  into  the  opening.  Small 
balls  of  scrap  gold  and  silver  are  sometimes  used  to  aid  in  filling  in 
when  the  space  is  of  considerable  size,  and  the  use  of  the  same  facilitates 
the  procedure  and  lessens  the  extent  of  shrinkage  which  would  take  place 
in  the  use  of  solder  alone.  The  use  of  balls  of  German  silver  or  copper 
is  also  permissible  if-  they  are  well  and  completely  covered  over  with 
the  gold  solder. 

In  finishing,  care  should  be  exercised  to  preserve  the  approximal 
contour,  in  order  that  contact  may  be  properly  restored  and  the  crown 
then  poHshed  and  mounted.     (Fig.  141  C.) 

These  crowns  are  sometimes  constructed  without  cusps,  but  such 
practice  is  to  be  condemned,  except  in  rare  instances  on  first  bicuspids,, 
because  the  usefulness  of  any  crown  is  usually  equal  in  importance  to 
cosmetic  effect. 


I/O 

a$c  of  Sadaic^Back  Ceetb. 

A  variation  of  metiiod  consists  in  employing-  the  so-called  saddle- 
back tooth  instead  of  the  facing,  and  while  this  style  of  construction  pos- 
sesses the  advantage  of  presenting  an  occlusal  surface  of  porcelain,  and 
thus  avoiding  any  display  of  gold,  the  more  esthetic  result  is  probably 
obtained  at  the  expense  of  strength,  as  the  thin  lingual  portion  of  such 
porcelain  teeth  is  usually  inherently  weak  and  more  or  less  easily  broken. 
Where  the  stress  of  occlusion  is  light,  however,  they  may  often  be  used 
to  good  advantage. 

In  their  application  a  selection  should  be  made 
PfOCCdure,  which  possesses  as  broad  a  neck  as  will  be  required 

to  m-ake  a  perfect  joint  with  the  cap,  and  which  will 
restore  the  contact  with  adjacent  teeth. 

It  should  then  be  ground  to  meet  these  requirements,  and  to  properly 
occlude  and  articulate,  after  which  a  single  backing  of  about  34  gauge 
pure  gold  should  be  well  adapted,  attached  by  bending  the  pins,  and 
trimmed  to  closely  follow  the  edges  of  the  porcelain  without  overhanging. 
(Fig.  142  A.) 


The  proper  relation  to  the  cap  should  now  be  obtained  (Fig.  142  B) 
and  securely  sustained  with  hard  wax,  and  the  crown  invested  in  such 
manner  as  to  have  the  porcelain  covered,  but  to  leave  the  backing  freely 
exposed. 

In  soldering,  a  sufficient  quantity  of  18  karat  solder  (in  addition  to 
the  use  of  balls  of  metal,  if  desirable),  to  afford  ample  and  adequate 
contour  of  the  approximal  and  lingual  surfaces,  should  be  used.  Fig. 
142  C  illustrates  the  finished  crown. 

An  ordinary  vulcanite  tooth   may  also  be  em- 

Use  Of  UulCdllite       ployed  in  similar  manner,  and  in  crowns  of  consider- 

t<Ctb.  able    length    sometimes    to    even    better    advantage, 

because  of  possessing  more  strength  in  the  lingual 

cusp,  due  to  the  greater  body  of  porcelain  surrounding  the  pins. 

In  their  use  the  heads  of  the  pins  should  be  compressed  between  the 
beaks  of  pliers,  or  cut  off,  and  the  lingual  surface  ground  smooth  to 
facilitate  the  adaptation  of  the  backing  and  the  above  ])rocedure  observed. 


171 
Application  or  Remoi^able  €rown$. 

Previous  to  the  modern  methods  of  successfully  treating  chronic 
alveolar  abscesses,  the  construction  of  crowns  which  could  be  temporarily 
removed  from  their  attachment  to  the  root  and  easily  replaced  was  advo- 
cated and  practiced  as  a  means  of  permitting;  the  necessary  therapeutic 
treatment  of  roots  so  affected. 

At  the  present  time,  however,  such  practice,  for  this  purpose,  has 
become  almost,  if  not  entirely,  obsolete,  and  the  application  of  such  crowns 
is,  in  consequence,  indicated  only  in  the  construction  of  removable  bridge- 
zvork ;  hence,  their  indications  and  usefulness,  together  with  the  various 
methods  of  construction  employed,  will  be  subsequently  considered. 

jflpplicatioti  to  Trredularitles. 

Since  some  cases  and  forms  of  irregularities  are  not  always 
amenable  to  the  usual  process  of  treatment  for  their  correction,  because 
of  the  age  of  the  patient,  the  poor  character  of  the  teeth,  their  position  in 
the  arch,  or  other  physiological  or  pathological  reasons,  it  sometimes 
becomes  warrantable  to  sacrifice  the  natural  crowns  and  effect  artificial 
substitution,  which  will  relieve  the  disfigurement  thus  occasioned. 

As  the  radical  or  injudicious  destruction  of  the  natural  crowns  of 
teeth  must  be  regarded  as  presenting  a  serious  aspect,  and  particularly 
when  involving  the  anterior  teeth,  where  they  are  necessarily  sacrificed 
to  the  gingival  line,  a  careful  study  of  the  existing  conditions  must  be 
made,  in  order  that  it  may  be  wisely  determined  that  such  a  procedure 
is  justifiable. 

The      two      general     classes     indicating     such 

Tit4iCiltiOJlS.  treatment    as    a    means    of    improving   both    useful- 

ness and   cosmetic   effect,  are  those  resulting  from 
malposition,  and  a  diminution  of  the  normal  space  caused  by  gravitation. 

malposition. 

Cases  are  not  uncommon  wherein  the  malposition  of  one  or  more 
teeth,  as  previously  indicated  in  Fig.  31,  may  be  best  corrected  by  the 
application  of  artificial  crowns,  but  the  achievement  of  successfully  artistic 
and  hygienic  results  in  such  instances  will  depend  much  upon  a  close 
observation  of  the  necessary  details  of  construction. 

In     the     construction     of     crowns     for      such 
Construction.  extreme  cases,  as  is  illustrated  in  Fig.  143,  the  cap  and 

dowel  should  be  adapted  to  the  root,  as  usual,  and 
-.the  bite  and  impression  taken  and  models  secured. 


172 

An  extension  from  the  cap  which  will  afford 
Extension  fOf  Support    a  close   adaptation   to   the  tissue,   and  a  practically 

Of  facing.  unyielding  support  to  the  facing  when  placed  in  its 

proper  position  of  alignment,  should  then  be  made  by 
burnishing  a  piece  of  pure  gold,  34  to  36  gauge,  to  the  model. 

When  the  desired  shape  and  conformation  have  been  obtained,  the 
extension  should  then  be  imbedded  into  the  model  at  least  equal  to  its 
thickness  by  first  marking  the  outline  and  then  uniformly  scraping  the 
surface. 

The  cap  should  then  be  detached  from  the  model  and  both  cap  and 
extension  again  placed  in  position  and  their  relation  sustained  with 
hard  wax. 

The  parts  should  now  be  removed  and  invested,  and  subsequently 
united  with  adequate  re-enforcement.  This  can  be  best  accomplished  by 
trimming  a  piece  of  clasp  metal  or  22  karat  plate,  28  to  30  gauge,  of 


proper  size  to  rest  upon  the  cap  and  cover  the  extension,  and  then  uniting 
the  whole  with  20  karat  solder. 

This  should  then  be  replaced  in  position  on  the  model,  and  the  crown 
completed  in  the  usual  manner. 

The  hygienic  qualities  possessed  by  crowns  so 
l^ygicnic  €on-         constructed  depend,  of  course,  upon  the  adaptation  of 
Siderations.  the  extension  and  facing  to  the  tissues  upon  which 

they  rest;  but  the  burnishing  (or  swaging,  if  more 
desirable)  of  the  extension  admits  of  a  close  conformation,  and  the 
scraping  of  the  surface  of  the  model  beneath  it  and  the  neck  of  the  facing 
so  increases  the  bearing  upon  the  tissue  as  to  usually  result  in  an  adapta- 
tion of  the  finished  crown  which  will  preclude  the  lodgment  and  accumula- 
tion of  debris. 

Diminution  of  normal  Space. 

A  condition  which  is  a  phase  of  malposition  caused  by  the  natural 
tendency  of  teeth  to  gravitate  toward  an  unoccupied  space  in  the  arch. 


is  illustrated  in  Fig.  144,  where,  from  the  extensive  destruction  of  the 
natural  crown  by  caries,  the  adjacent  teeth  have  moved  together,  until 
the  space  formerly  existing  in  the  normal  relation  is  much  reduced. 

In  such  conditions,  when  involving  any  of  the  ten  anterior  teeth,  the 
application  of  an  artificial  crown  of  adequate  and  proportionate  size  would 
be  impossible,  of  course,  unless  sufficient  accommodation  be  previously 
gained  by  separating  the  teeth,  and  such  a  procedure  is  indicated,  and 
becomes  essentially  necessary,  if  the  highest  artistic  results  are  to  be 
obtained. 

In  separating  the  teeth  in  such  instances  the 
Separation  of  Cecfb.  application  of  a  simple  regulating  appliance  may 
become  necessary  if  any  great  deal  of  space  is  to 
be  gained,  and  when  the  desired  space  has  been  obtained  it  may  be  pre- 
served during  the  construction  of  the  crown  by  wedging  with  a  small 
piece  of  wood,  or  by  tightly  packing  with  gutta  percha  or  temporary  stop- 
ping during  intervals  between  sittings. 


Sufficient  separation  may  often  be  secured  in  a  more  simple  manner 
by  trimming  and  closely  fitting  a  wedge  of  soft  wood,  previously  com- 
pressed in  a  small  bench-vise,  into  the  space.  If  the  wood  is  properly 
trimmed  to  follow  the  outlines  of  the  adjacent  teeth,  so  that  it  may  be 
worn  with  some  degree  of  comfort,  and  then  tightly  fitted  into  the  space, 
having  the  surfaces  approximating  the  adjacent  teeth  slightly  concaved 
to  hold  it  in  position,  and  the  grain  placed  parallel  with  the  long  axis  of 
the  tooth,  the  absorption  of  moisture  will  usually  produce  an  expansion 
sufficient  to  create  the  space  desired.  This  may  also  be  increased  some- 
what by  the  use  of  an  intervening  layer  of  cotton  or  tape  when  necessary. 

Jlpplication  of  tDc  Tntradcntal  Band. 

For  the  purpose  of  avoiding  the  necessary  peripheral  preparation  of 
the  root  and  the  possible  irritating  influence  of  a  band,  and  at  the  same 
time  securing  the  additional  stability  afforded  by  the  latter  to  the  attach- 
ment of  a  dowel  crown,  the  intradcntal  band  has  been  devised. 

The  principle  involved  is  similar  to  that  of  the  original  Biittner  crown 
in  which  the  periphery  of  the  root  was  trephined  so  as  to  form  a  seat 


174 


for  the  accommodation  of  the  band.  In  the  appHcation  of  the  uitradental 
band,  however,  a  groove  is  trephined  into  the  root  midway  between 
the  pulp  canal  and  the  periphery,  and  a  band  subsequently  fitted  into 
the  groove. 

The  design  was  probably  originally  suggested  and  patented  by  Dr. 
Moses  Rynear,  of  New  York,  in  1886,  but  subsequent  patents  have  been 
obtained  on  modifications  of  this  by  Dr.  J.  Leon  Williams,  of  London, 
and  Dr.  B.  J.  Cigrand,  of  Chicago,  in  both  of  which  the  principle  is  the 
same,  but  the  application  and  details  differ  somewhat. 

While  the  advantages  claimed  by  the  advocates  for  this  mode  of  con- 
struction are  doubtless  desirable,  they  are  obtained  at  the  expense  of  the 
integrity  of  the  basal  portion  of  the  root,  and  for  this  reason  are  indicated 
only  on  large,  strong  roots,  entirely  free  from  decay,  and  will  probably 
never  become  more  generally  applicable. 


/vy./4^.  •  Fixj.l46. 

The  design  and  method  devised  and  employed 
Ulilliams'S  method,     by  Dr.  Williams  consists  of  a  series  of  ready-made 
platinum  caps  and  dowels  in  graded  sizes,  together 
with  suitable  trephines  and  root  canal  drills. 

In  the  application  of  this  style  of  crown  the  root 
Jlpplication.  is  prepared  as  usual  for  a  dowel  crown,  without  a 

band.  A  cap  (Fig.  145  A)  of  suitable  and  propor- 
tionate size  is  then  selected  from  the  series,  and  the  trephine  and  drill  of 
corresponding  size  selected. 

The  canal  is  first  enlarged  with  the  drill  (Fig.  145  B)  to  accommodate 
the  dowel,  and  the  trephine  then  used  to  cut  the  groove  for  the  reception 
of  the  band,  and  the  proper  relation  between  the  two  is  secured  by  the 
guide  post  in  the  center  of  the  trephine.     (Fig.  145  C.) 

When  the  cap  has  been  thus  closely  adapted  to  the  canal  and  groove. 


175 

the  surplus  floor,  which  is  about  34  to  36  gauge,  should  be  trimmed  to 
follow  the  peripheral  outline,  and  burnished  to  the  desired  adaptation  with 
the  entire  surface  of  the  root. 

The  bite  and  impression  should  then  be  taken  and  the  crown  com- 
pleted in  the  usual  manner  and  mounted  with  cement. 

The  facility  with  which  these  ready-made  caps  may  be  secured  and 
adapted  to  the  root  in  the  use  of  this  method  expedites  the  detail  of 
construction,  but  the  band  seems  too  thin  and  narrow  and  the  dowel 
too  slender  to  afTord  adecjuate  strength  and  stability  to  a  crown  of  average 
requirements. 

The  method  devised  by  Dr.  Cigrand  constitutes 
(KIgrand'S  method,     making  the  band  and  cap  and  adjusting  the  dowel, 
and   the    necessary    outfit   consists   of   two    sizes   of 
trephines  and  a  measurement  gauge,  as  previously  illustrated  in  a  consid- 
eration of  the  treatment  of  "fractured  roots." 

In  the  application   of  this  method   the   root  is 

Application.  prepared  as  indicated,  and  the  groove  cut  as  deep  as 

practicable  with  the  trephine  of  proportionate  size. 
The  band  is  then  cut  the  exact  length  indicated  by  the  measurement  guide 
for  the  size  trephine  used,  about  one-eighth  of  an  inch  wide  and  of  30 
gauge  gold,  22  karat,  or  platinum,  made  in  circular  form,  the  edges 
abutted,  and  soldered  with  a  very  small  bit  of  solder. 

It  should  then  be  fitted  over  the  end  of  the  measurement  mandrel  to 
give  it  the  proper  form,  and  adjusted  to  position  in  the  groove  by  gently 
forcing  to  place. 

The  surplus  end  extending  from  the  root  should  be  allowed  to  remain 
to  facilitate  removal  and  filed  smooth  on  a  parallel  line  with  the  surface 
of  the  root.  It  should  then  be  removed  and  soldered  to  a  floor  of  pure 
gold  or  platiimm,  34  gauge,  somewhat  larger  than  necessary,  with  a 
minimum  of  solder. 

The  edge  of  the  band  previously  fitted  into  the  groove  should  now 
be  trimmed  away  until  the  fioor  rests  firmly  against  the  root,  when  in 
position,  after  which  it  should  be  trimmed  and  burnished  to  the  proper 
adaptation. 

The  canal  should  now  be  prepared,  the  dowel  fitted,  and  then  soldered 
to  the  cap,  as  indicated,  and  the  crown  completed  in  the  usual  manner. 

The  completed  crown  and  the  relation  it  should  bear  to  the  root  in 
both  of  these  methods  is  illustrated  in  Fig.  146. 

Kcpairlnd  ana  Kemovlnd. 

Because  of  the  presence  of  porcelain,  and  the  consequent  more  or 
less  frequent  occurrence  of  fractured  facings  as  a  result  of  accident,  in- 


1/6 

adequate  protection,  or  faulty  articulation  and  occlusion,  as  well  as  for 
the  purpose  of  replacement  or  substitution,  it  often  becomes  necessary 
to  repair  this  style  of  crown,  or  to  remove  it  from  its  attachment  to  the 
root. 

Kepairmg. 

The  presentation  of  fractured  or  broken  facings  on  crowns  and 
bridges  constitutes  a  large  per  cent  of  the  failures  requiring  such  atten- 
tion, and  where  the  work  remains  otherwise  in  good  condition,  and  is 
secure  in  its  attachment,  repair  may  be  effected  in  an  artistic  manner  bv 
replacing  the  facings  without  removing  the  piece. 

In  the  replacement  of  facings,  several  good  and 

Kcplacctnent  of         reliable  methods  are  employed,  but  a  selection  of  the 

TacitlflS.  best  or  most  desirable  one  will  depend  much  upon 

the  construction  of  the  work  and  the  requirements  of 

the  case,  as  well  as  the  individual  preference  of  the  operator. 

When  such  a  procedure  is  indicated,  where  the  work  has  been  con- 
structed by  the  ordinary  method,  all  remaining  particles  of  porcelain  sur- 
rounding the  pins  should  first  be  broken  and  removed.  This  can  be  quite 
easily  accomplished  with  excising  forceps,  cutting  pliers  or  chisels,  after 
which  the  projecting  pins  should  be  cut  away  and  ground  down  flush 
and  even  with  the  surface  of  the  backing,  with  a  sharp,  round,  or  oval, 
plain,   or  plug-finishing  bur. 

The   method  usually   and,   perhaps,    most   com- 
Uswal  111«tl)0d.         monly  employed  consists  of  securing  the  attachment 
of  the  replaced  facing  by  simply  bending  or  clinching 
the  pins  upon  the  lingual  surface  of  the  backing. 

In  this  procedure  a  facing  of  the  required  size, 

Proc<dwr{.  shape  and  color  should  be  selected,  and  the  backing 

then  properly  perforated  to  admit  of  its  adjustment. 

The  accurate  position  of  the  perforations  may  be  easily  ascertained, 

and  designated,  by  first  coating  the  surface  of  the  backing  with  a  thin 

film  of  melted  wax,  and  then  pressing  the  ends  of  the  pins  into  it,  after 

noting  that  they  have  been  made  parallel  zvith  each  other,  and  that  the 

facing  is  held  in  its  proper  relation  to  the  backing  and  adjacent  teeth  or 

facings. 

When  the  exact  location  has  been  thus,  or  otherwise,  designated,  the 
perforations  may  be  made  with  a  small  spear-pointed  drill,  and  subse- 
quently enlarged  to  the  proper  proportions  to  receive  the  pins  with  a 
round  or  fissure  bur,  or  twist  drill,  of  corresponding  diameter.  While 
they  should  be  large  enough  to  readily  admit  of  the  reception  of  the  pins, 


177 

the  fit  should  be  sufficiently  close  to  render  the  attachment  secure,  and 
preclude  the  subsequent  loosening  of  the  facing. 

The  facing  should  be  then  adjusted  to  position  and  ground  to  fit 
the  backing,  and  to  meet  the  requirements  of  length,  occlusion  and  align- 
ment ;  and  this  may  often  be  somewhat  facilitated  by  bending  the  incisal 
or  occlusal  edge  of  the  backing,  with  pliers,  until  a  more  favorable  shape 
presents. 

When  the  adaptation  has  been  completed,  it  should  be  noted  that  the 
pins  extend  through  upon  the  lingual  surface  sufficiently  far  to  admit  of 
securing  a  firm  attachment  by  bending  their  surplus  ends ;  and  in  the 
event  of  this  being  prevented  by  the  thickness  of  the  backing,  its  lingual 
■surface  should  be  previously  ground  down  with  small  carborundum 
stones,  or  burs,  until  such  security  is  made  possible. 

The  surfaces  of  the  facing  and  backing  should  then  be  thoroughly 
cleaned,  slightly  roughened  and  dried  with  alcohol  or  chloroform,  when 


the  backing  should  be  covered  with  cement  mixed  fairly  stiff,  and  the  fac- 
ing adjusted  to  position,  where  it  should  be  held  firmly  while  the  ends 
■of  the  pins  are  being  bent  over  upon  the  backing  with  pliers. 

Moisture  should  then  be  excluded  from  the  cement  until  it  has  thor- 
oughly crystallized,  when  the  edge  of  the  backmg  should  be  finished 
down  close  to  the  porcelain,  with  disks,  and  the  pins  flattened  with  small 
.  stones  until  presentmg  a  more  or  less  smooth  and  continuous  contact  with 
the  backing.  The  latter  may  usually  be  done  to  the  best  advantage,  and 
with  the  least  danger  of  fracturing  the  cement,  at  a  subsequent  sitting. 


Brewer's  metbod. 

The  above  procedure  is  much  simplified  and  greatly  facilitated  by 
the  use  of  a  pair  of  "riveting  forceps,"  designed  for  the  purpose  of  rivet- 
ing the  ends  of  the  pins  down  close  upon  the  backing,  by  Dr.  Frank  A. 
Brewer,  Sr.,  of  King  City,  Cal.     (Fig.  147.) 


178 

One  beak  of  these  forceps  presents  a  corrugated  soft  rubber  pad,  on? 
an  adjustable  joint,  which  admits  of  its  close  adaptation  to  the  facing, 
at  any  angle  or  position,  while  the  other  presents  a  small  concave  steel 
point,  also  likewise  adjustable,  which  engages  the  end  of  the  pin. 

In  the  application  of  this  method  of  attaching 

Hppltcation.  the  facing,  the  perforations  should  be  made  and  the 

facing  adapted,  as  indicated,  and  then  the  ends  of 
the  pins  or  the  backing  should  be  sacrificed  until  the  former  project  only 
about  1/32  of  an  inch  beyond  the  surface  of  the  latter. 

The  lingual  surface  of  the  perforations  should  now  be  somewhat 
countersunk  with  a  round  bur  of  proper  size  used  in  a  right  angle  hand- 
piece. 

When  the  facing  has  been  well  adapted,  it  should  be  placed  in  posi- 
tion with,  or  without,  cement,  and  the  forceps  then  adjusted,  when  a  slight 
pressure  upon  the  handles  applied  during  a  rotary  or  swing- 
ing movement  of  the  arm  will  effect  an  expansion  of  the  diameter,  and  a 
compression  of  the  heads  of  the  pins,  until  a  very  secure  and  finished- 
attachment  results,  with  little  or  no  danger  of  fracturing  the  porcelain.. 

Underwooa's  ana  mitcbeirs  mctbod. 

The  method  advocated  by  Dr.  C.  J.  Underwood,  of  Elgin,  111.,  which 
in  similar  detail  has  also  been  employed  for  a  number  of  years  by  Dr. 
Wm.  Mitchell,  of  London,  England,  is  also  valuable  and  useful,  and  is. 
particularly  applicable  to  those  cases  where  the  old  backing  was  origin- 
ally, or  has  been  worn  down  until,  too  short  to  afirord  the  proper  pro- 
tection to  the  porcelain  along  the  incisal  or  occlusal  edge. 

This  method  consists  of  adapting  a  duplicate  backing  to  the  lingual 
surface  of  the  old  backing,  and  then  attaching  it  to  the  pins  of  the  facing 
with  solder,  and,  wherever  the  occlusion  will  admit,  its  application  may 
be  made  with  very  artistic  results,  and  with  a  maximum  of  strnegth. 

In  the  procedure  incident  to  the  application  of 

Jlpplication.  this   method,   the   remaining  porcelain   and  project- 

ing ends  of  the  pins  should  be  removed  from  the  old 
backing,  and  slots  or  grooves  sufficiently  wide  to  accommodate  the  pins 
of  the  new  facing  and  extending  from  the  incisal  or  occlusal  end  toward 
the  cervical  to  a  point  which  will  admit  of  its  proper  adjustment,  should 
be  made  with  a  cross-cut  or  plain  fissure  bur.     (Fig.  148  A.) 

The  location  of  these  grooves  may  be  accurately  designated,  as  pre- 
viously indicated,  and  the  bur  used  should  be  of  a  diameter  as  similar  tO' 
that  of  the  pins  as  possible. 

The  facing  selected  is  then  ground  to  the  required  and  desired  adap- 
tation, and  afterward  backed  up  with  pure  gold,  about  34  gauge.     This. 


'79 

should  be  well  adapted  to  the  incisal  or  occlusal  end  of  the  facing,  and 
trimmed  to  closely  follow  its  outlines.  The  cervical  edge  of  the  backing 
should  be  then  drawn  away  from  its  contact  with  the  porcelain  toward 
the  extreme  ends  of  the  pins,  so  as  to  straddle  or  pass  to  the  lingual  sur- 
face of  the  old  backing. 

Facing  and  backing  should  be  then  adjusted  to  position  on  the  crown 
or  bridge,  and  the  latter  burnished  to  a  close  conformation  with  the  lin- 
gual surface  of  the  old  backing,  which,  if  too  thick  to  allow  the  pins  to 
project  slightly  through  the  new  backing,  should  be  ground  until  admit- 
ting of  same.      (Fig.  148  B.) 

While  it  is  best  to  secure  this  adaptation  directly  in  the  mouth,  it  may 
also  be  accomplished  with  reasonable  accuracy  by  taking  an  impression 
of  the  crown  and  adjacent  teeth,  after  the  grooves  have  been  cut,  with 
gutta  percha,  and  obtaining  from  it  a  fusible  metal  working  model  for 
the  purpose. 


Fig.  1 48. 


The  adaptation  should  then  be  sustained  by  the  use  of  wax  or  tem- 
porary stopping,  and  the  facing  and  backing  gently  detached,  and  in- 
vested with  sufficient  care  to  insure  the  thorough  penetration  of  the  in- 
vestmeni-  material  into  the  intervening  space  between  the  two. 

The  relation  should  now  be  permanently  sustained  by  soldering  the 
backing  to  the  exposed  ends  of  the  pins,  and  then  re-enforcing  it  as  much 
as  the  occlusion  will  admit,  after  which  it  should  be  finished  and  polished 
(Fig.   148  C.)   and  then  mounted  with  cement. 

While  the  detail  of  this  method  is  necessarily  somewhat  circuitous, 
the  procedure  afifords  a  most  secure  and  finished  result. 


Dwidbfs  method. 

Dwight's  method,  which  has  been  previously  mentioned  and  illus- 
trated in  connection  with  replaceable  and  detachable  facings,  is  also  ap- 
plicable to  the  repair  of  work  where  the  ordinary  two-pin  facing  has  been 
used. 


i8o 

When   the   remaining  porcelain   and  projecting 

Jlpplication.  ends  of  the  pins  have  been  removed,  a  facing  of  this 

particular   style   should   be   selected   and   ground   to 

place,  in  which  the  procedure  is  facilitated  because  of  the  absence  of  any 

pins. 

After  the  proper  adaptation  h^s  been  secured,  the  "finder,"  which 
is  included  among  the  necessary  instruments  for  doing  this  special  work, 
and  consists  simply  of  a  base  or  shank  which  fits  into  the  socket  in  the  fac- 
ing, and  tapers  to  a  central  point,  should  be  adjusted  to  position.  (Fig. 
149  A.) 

This  affords  a  means  of  designating  the  exact  location  for  a  single 
perforation  in  the  old  backing,  by  applying  sufficient  pressure,  or  by  the 
use  of  a  thin  film  of  wax,  with  the  facing  held  in  its  proper  relation. 


F/Q.1^9, 


A  small  perforation  should  first  be  made  at  this  point  with  a  drill  or 
round  bur,  and  this  then  suitably  enlarged  with  a  twist  drill,  and  subse- 
quently threaded  with  a  tap,  both  of  which  are  also  included  in  the  outfit. 
(Fig.  149  B.) 

The  threaded  shank  of  the  "attachment"  should  be  now  adjusted  to 
the  "holder"  (Fig.  149  C),  and  screwed  into  place  until  its  base  rests 
firmly  against  the  backing,  and  the  spring  ends  are  brought  into  proper 
position  to  engage  the  facing.  If  the  latter  is  impossible  at  the  first  trial, 
the  attachment  should  be  unscrewed  and  removed,  and  the  backing  im- 
mediately  surrounding  the  perforation  ground  away. 

By  this  means  the  threaded  area  may  be  gradually  diminished 
until  the  required  relation  is  obtained,  after  securing  which  the  projecting 
end  of  the  attachment  upon  the  lingual  surface  is  ground  down  even 
with  the  backing,  and  the  facing  then  mounted  with  cement. 


i8i 

Bryant's  method. 

Among  the  most  ingenious  methods  used  in  replacing  facings  is  the 
one  devised  by  Dr.  Emory  A.  Bryant,  of  Washington,  D.  C.  This  con- 
sists of  countersinking  the  old  backing  from  the  lingual  surface;  then 
threading  the  pins  of  the  facing,  and  attaching  it  to  the  backing  by  means 
of  a  corresponding  countersunk  nut. 

The  latter  are  procurable  in  ready-made  form,  as  are  also  the  neces- 
sary instruments  for  doing  the  work,  and  while  this  method  affords  a  se- 
cure means  of  attachment,  the  detail  is  somewhat  exacting  and  requires 
considerable  time. 

It  is  perhaps  more  generally  applicable  to  replacing  facings  on  bicus- 
pids, or  even  molars,  in  bridgework,  than  to  the  anterior  teeth,  because 
the  strength  of  the  attachment  increases,  of  course,  in  proportion  to  the 
thickness  of  the  backing,  which  in  this  particular  region  is  necessarily 
governed  by  the  occlusion,  yet  it  may  often  be  applied  here. 


Fic].  150. 


(t 


In  the  application  of  this  method,  the  remain- 
Jfpplication.  ing    porcelain,    and    projecting    ends    of    the    pins, 

should  be  removed,  the  new  facing  selected,  and  the 
backing  accurately  perforated  for  the  reception  of  the  pins,  as  previously 
indicated ;  after  which  the  facing  should  be  ground  to  the  required  adap- 
tation. 

The  perforations  in  the  backing  are  now  countersunk  from  the 
lingual  surface  with  the  countersinking  reamer  in  right  angle  handpiece, 
until  they  are  suitably  enlarged  to  receive  the  small  end  of  the  nut  and 
admit  of  bringing  it  flush  and  even  with  the  labial  or  buccal  surface  of 
the  backing  (Fig.  150  A.),  care  being  observed  that  it  shall  not  protrude 
to  the  least  extent. 

When  this  has  been  accomplished,  the  pins  of  the  facing  should  be 
threaded,  first  with  the  large  size  tool,  or  screw-plate,  and  finally  with 
the  smaller  one ;  in  this  procedure  care  must  be  exercised  to  prevent 
twisting  off  the  pins.  The  use  of  a  little  oil  will  preclude  this  and  facili- 
tate the  work. 


l82 

The  nuts  are  made  of  a  well  alloyed  gold,  corresponding  in  size  with 
the  reamer,  and  are  tapped  to  fit  the  threaded  pins  of  the  facing,  to  each 
of  which  the  respective  nuts  should  be  first  adjusted  to  place,  before  the 
permanent  attachment  of  the  facing  to  the  backing  is  made. 

The  backing  should  then  be  coated  with  cement,  the  facing  placed 
in  position  and  the  nuts  adjusted  to  the  pins  (Fig.  150  B)  (which  may  be 
facilitated  by  a  "holder"),  and  alternately  screwed  to  place  with  the 
wrench,  avoiding  undue  force,  until  both  are  firmly  fixed  in  their  proper 
relation  and  the  attachment  is  secure. 

The  projecting  ends  of  the  nuts  and  pins  should  now  be  ground 
down,  with  small  carborundum  stones,  until  smooth  and  continuous  with 
the  backing,  and  the  surface  subsequently  polished  with  disks.  (Fig. 
150  C.) 

The  nuts,  and  a  wrench,  suitable  for  their  adjustment,  are  illustrated 
in  Fig.  150  D. 

The   replacement  of  facings  on  bicuspids  and 
Kcplacins  Bicuspid      molars,  although  perhaps  most  generally  confined  to 
on  molar  facings.       bridgework,  will  be  also  considered  in  this  connec- 
tion.    This  is  usually    a    somewhat    more    difficult 
procedure,  because  of  the  increased  thickness  of  the  gold  forming  the 
cusps  and  lingual  contour,  and  surrounding  the  area  where  the  attach- 
ment must  be  secured,  which  usually  precludes  a  projection  of  the  ends 
of  the  pins. 

Where  it  may  not  be  desirable  to  employ  the  Bryant  method,  or 
where  the  same  may  seem  contraindicated,  or  be  impracticable,  the  most 
simple  and  commonly  applied  procedure  is  to  cut  a  countersunk  aperture 
in  the  old  backing  with  drills  and  burs,  of  proportions  suffici-ently  large  to 
admit  and  accommodate  both  pins  of  an  ordinary  facing. 

The  facing  should  then  be  selected  and  ground  to  the  required  adap- 
tation, and  the  ends  of  the  pins  bent  somewhat  diverging  from  each 
other,  or  to  present  short  sharp  right  angle  turns,  which  may  be  passed 
into  the  aperture  when  the  facing  is  slightly  inverted,  and  which  will 
hook  over  its  edge  upon  bringing  the  facing  into  proper  position. 

This  will  increase  the  integrity  and  strength  of  the  subsequent  at- 
tachment with  cement,  and  the  same  may  be  further  facilitated  by  serrat- 
ing  or  roughening  the  surface  of  the  backing  with  a  sharp  wheel  or  in- 
verted cone  bur. 

Facing  and  backing  should  now^  be  thoroughly  dried,  and  the  mount- 
ing made  with  cement  mixed  fairly  thick,  and  with  an  observation  of  the 
previously  mentioned  details  in  this  connection,  reasonably  permanent 
results  may  be  obtained. 

Where  adequate  mechanical   retention  is  possible,  plastic  amalgam 


i83 

may  often  be  used  to  good  advantage,  and  is  sometimes  preferable  to 
cement. 

In  those  cases  where  the  old  backing  has  been 

Kcplaccmcnt  of        almost,  or  entirely,  destroyed,  so  that  sufficient  oppor- 

Tacing  and  Baching,    tunity   for  securing  adequate  anchorage  for  a  new 

facing,   by   any   of   these   methods,   is   doubtful ;   or 

where  the  cap  and  dowel  have  become  detached  from  the  root,  or  may 

be  removed  without  mutilation  or  destruction,  repair  can  almost  invariably 

be  best  effected  by  cutting  the  remaining  backing  oil'  close  to  the  base  of 

the  cap  with  a  fine  saw,  excising  forceps,  carborundum  stones  or  files, 

and  attaching  the  facing  and  its  new  backing  by  investing  and  soldering 

in  the  usual  manner. 

The  mechanical  saw  (Fig.  151)  will  usually  be  found  best  adapted 
to  such  purpose,  and  is  an  indispensable  device  to  a  well-equiped  labo- 
ratorv. 


Ficf.  151. 


This  procedure  will  afford  opportunity  for  securing  the  strongest 
and  most  artistic  results  wherever  the  adaptation  between  cap  and  root 
is  sufficiently  good  to  warrant  the  use  of  tlie  old  cap,  and  where  this  is 
doubtful,  a  new  crown  should  be  constructed  throughout. 

In  such  instances  the  procedure  should  consist 
Procedure.  in  first  removing  the  remaining  cement  from  the  in- 

terior of  the  cap,  with  burs,  and  then  thoroughly 
cleansing  in  acid.  The  dowel  should  now  be  grasped  firmly  in  a  jeweler's 
pin-vise  (Fig.  152)  (which  is  a  most  useful  instrument  in  this  work), 
and  the  backing  removed  up  sufficiently  close  to  the  base  of  the  crown 
to  offer  no  obstruction  to  the  proper  adjustment  of  the  facing. 

The  cap  should  be  then  placed  in  position  upon  the  root,  and  the 
usual  "bite"  and  impression  taken,  when  the  repair  can  be  made  upon 
the  models  in  accordance  with  the  usual  method  of  construction  from 
this  point  on. 


i84 

Rcttioving. 

The  removal  of  this  style  of  crown  may  often  become  necessary  for 
the  purpose  of  replacement  or  substitution,  and  while  the  procedure  may 
be  found  somewhat  difficult  in  those  cases  where  the  attachment  remains 
secure,  it  may  be  effected  by  one  or  the  other  of  the  following  methods : 


Fiq.152. 


Use  of 
excising  Torccps. 


The  easiest  and  most  convenient  method,  when- 
ever applicable,  is  to  first  crush  and  remove  the 
facing  if  present,  and  then  grasp  the  remaining^ 
backing  up  close  to  the  base  of  the   crown,  where 

it  is  thickest,  with  the  beaks  of  a  pair  of  excising 

forceps   (Fig.  153)   (which  is  also  a  most  useful 

instrument),   and   then    gradually    and    slowly 

fracture  the  cement   and   destroy  the  integrity 

01  the  attachment,  by  exerting  a  slight  pressure 

upon  the  handles  and  a  lateral  or  rotary  move- 
ment upon  the  crown. 

The  power  of  the  lever,  in  this  application, 

will  usually  result  in  the  ready  detachment  of 

the  crown  from  the  root,  but  force  should  be 

applied  slowly  and  with  exteeme  care,  in  order 

to  prevent  injury  to  the  peridental  membrane, 

or  the  removal  of  the  root. 

In  the  event  of  loosening  the    root,    because 

of  its  instability,  or  of  the  strength  and  integrity 

of  the  attachment    of    the    crown,    tvhich    will 

alzvays  cause  a  slight  gingival  hemorrhage,  this 

procedure  should  be  at  once  discontinued  before 

injury  has  resulted,  and  another  one  requiring 

less  force  will  be  demanded. 

When  the  above  method 
seems  contraindicated,  or 
proves  ineffective,  or  where 

the  backing  has  been  previously  destroyed  until  no  opportunity  is  afforded 

for  its  application,  the  removal  may  be  facilitated  and  made  easy  and 

devoid  of  danger,  by  first  separating  the  can  from  the  dowel. 


Separating 
Cap  and  Dowel. 


fiqJS3. 


i85 

This  may  be  done  by  drilling  through  the  Ijase  oi  the  crdw  n  at  a  point 
approximating  the  periphery  of  the  dozvel,  until  the  root  has  Ijeen  reached, 
with  a  small  drill  or  round  bur,  and  then  severing  the  cap  from  iIk-  dowel 
with  burs  of  a  larger  size. 

When  this  has  been  accomplished,  if  it  is  desirable  to  utilize  the  cap 
again,  it  should  be  worked  loose  and  lifted  off  with  pliers  ;  but  if  no  further 
use  is  to  be  made  of  it,  the  procedure  may  be  facilitated  by  destroying 
the  continuity  of  the  band  with  excising  or  crown  slitting  forceps,  or  a 
small  bur. 

The  remaining  dowel  should  then  be  removed  by  cutting  away  the 
surrounding  cement  with  very  small  round  burs,  until  it  may  be  gripped 
with  strong  small-pointed  pliers,  and  the  entire  length  removed. 

In  this  procedure,  however,  care  must  be  exercised  to  avoid  per- 
forating the  root,  or  breaking  ofif  the  dowel  at  a  point  which  will  preclude 
the  removal .  of  the  remaining  end. 

Jlccuracy  in  model  makind. 

Whilst  much  emphasis  has  already  been  placed  upon  the  necessity  for 
accuracy  in  impression  taking  and  model  making,  these  features  of  the 
procedure  are  of  such  paramount  importance  as  to  make  special  emphasis 
warrantable. 

Throughout  the  entire  procedure  incident  to  the  construction,  or  even 
the  repair,  of  any  style  of  crown,  and  particularly  of  those  for  the  anterior 
teeth,  a  good  impression  and  an  accurate  model  are  prerequisites  to  suc- 
cess, because  by  this  means  the  work  may  be  transferred  from  the  mouth 
to  the  laboratory  with  all  the  exactness  which  successful  achievement 
demands. 

In  order  that  the  very  best  results  may  be  obtained  with  the  greatest 
degree  of  accuracy  and  expediency,  the  impression  should  always  be  taken 
in  plaster  because  of  its  being  the  most  reliable  material ;  and  the  model 
obtained  from  it  must  support  and  sustain  the  cap — or  caps — in  the  proper 
and  exact  relation  which,  when  in  the  mouth,  they  bear  to  the  roots,  to  the 
adjacent  teeth,  and  to  the  gingival  outline  of  the  tissues. 

The  facility  with  which  the  cap,  or  caps,  may  be  detached  or  removed 
from  the  model — and  in  such  manner  as  to  admit  of  ready  and  accurate 
readjustment — depends  largely  upon  the  observation  of  the  detail  of  filling 
the  interior  of  the  cap,  and  covering  the  dowel,  with  a  thin  film  of  melted 
wax  just  previous  to  filling  the  impression,  as  is  illustrated  in  Fig.  154 
for  a  lateral  and  in  Fig.  155  for  a  bicuspid  crown. 

This  simple  precaution  readily  admits  of  the  easy  detachment  of  the 
cap  from  the  model,  and  of  its  accurate  subsequent  replacement,  both  of 


t86 

which  remove  any  difficuUies  or  obstacles  incident  to  the  construction  and 
assemblage  of  the  parts,  and  to  the  subsequent  removal  and  investment  of 
the  piece;  and  the  preservation  of  the  model  thus  made  possible,  affords 
opportunity  for  final  trials  at  any  time  during  or  after  the  completion  of 
the  case,  all  of  which  are  advantageous  features. 


Ficj./sa. 


Fiq.  IS5. 


When  the  model  has  been  separated  from  the  impression,  the  cap  may 
then  be  easily  removed  by  slightly  warming  the  surplus  end  of  the  dowel 
over  a  flame,  and  grasping  it  firmly  with  flat  beak  pliers,  when  a  straight 
pull  will  quickly  detach  it,  and  yet  leave  an  outline  of  such  accuracy  as  to 
admit  of  its  easy  and  correct  readjustment  to  position.     Fig.  156. 


Fic/.  156. 


Ficf.lSl, 


After  thus  removing  the  cap  the  wax  should  be  burned  out,  and  it 
should  then  be  thoroughly  cleaned  in  the  acid  bath  to  insure  the  further 
removal  of  all  residue  from,  and  perfect  cleanliness  of,  the  metal,  when 
it  may  be  placed  upon  the  model,  or  laid  aside  for  the  time  being,  if  prefer- 


I  St 


ahk',  and  the  wax  "l)itc"  adjusted  to  jx-sition,  l-i|^^  157.  and  the  case  then 
mounted  u])on  the  articulator. 

When  more  than  one  crown  is  bein^r  constructed  for  the  same  mouth 
at  the  same  time,  one  model  and  "bite"  is  all  that  is  necessary,  but  each 
individual  crown  should  always  l)e  separately  invested  and  soldered. 

\\  hile  the  ordinary  crown  articulator  previously 
TtnproPCd  illustrated  in  Fig.  71  may  be  used,  and  will,  of  course, 

Articulators.  serve  the  jnirpose,  better  results    from  the  view])oint 

of  a  more  accurate  articulation,  which  is  decidedly 
advantageous  ])articularly  when  porcelain  is  to  be  employed  in  anv  man- 
ner, may  be  obtained  from  the  use  of  the  more  imj^roved.  and  so-called 
anatomical,  articulators,  which  are  designed  more  especially  for  bridge- 
work,  and  which  admit  of  a  slight  forward,  backward  and  lateral  move- 
ment. 

Two  designs  j^osscssing  these  features  which  seem  to  be  eminently 
practical  are  Kerr"s  Improved  crown  and  l^ridge  articulator,  manufac- 
tured by  Mr.  M.  M.  Kerr,  of  Detroit,  Mich.,  and  the  design  manufactured 
by  the  Blue  Island  Specialty  Co.,  of  Blue  Island.  111.,  each  of  which  are 
simple  and  inexpensive. 


ZM  Plate  and  Dowel  grown. 


CHAPTER  X. 

Advantages.       Indications,       Requirements.       Method    of     Construction;     Typicall 
Cases ;    Root    Preparation ;    Six    Anterior     Teeth,    Bicuspids.      Adaptation 
of  Plate,  Adjustment  of  Dowel.     Extensive  Destruction  of  Root: 
Swaging   Plate ;   Impression  of  Root,  Dies,  Dowels.     Con- 
struction upon  Models. 


In  view  of  the  great  variation  of  conditions  presenting,  and  because 
of  the  possible  objections  to  a  band  which  may  be  made  with  reason  and 
consistency  in  some  instances,  and  in  certain  classes  of  cases;  together 
with  the  advantages  to  be  derived  from  a  close  and  more  or  less  perfect 
adaptation  of  the  base  of  the  crown  to  the  end  of  the  root,  and  the  esthetic 
possibilities  afforded — the  plate  and  dowel  crown  differing  from  the  pre- 
ceding style  by  the  absence  of  a  band,  and  consisting  simply  of  a  plate 
and  dowel  base,  has  a  wide  range  of  application  and  usefulness,  and  is 
somewhat  extensively  employed  in  the  restoration  of  the  ten  anterior 
teeth,  and  even  sometimes  on  the  molars. 

When    the   employment    of    a   band    is    contra- 

JldVantad^S.  indicated,  or  seemingly  undesirable,  such  a  style  of 

construction  affords  the  advantage  of  securing  a 
closer  line  of  junction  between  the  crown  and  the  root,  by  burnishing  or 
swaging  a  thin  metal  base  and  .then  adjusting  a  dowel  and  completing 
the  crown  in  the  usual  manner,  than  cotild  possibly  result  from  grinding 
one  surface  to  conform  closely  with  another,  such  as  becomes  necessary 
in  the  application  of  the  various  forms  of  ready-made  porcelain  crowns. 

While  the  esthetic  possibilities  thus  afforded  are  also  desirable,  the 
principal  features  lie  in  the  conservation  of  tooth  structure,  the  preserva- 
tion of  the  normal  condition  of  the  gingivae,  and  the  degree  of  perma- 
nency that  must  result  from  obtaining  a  perfect  joint  betAveen  the  crown 
and  both  the  base  and  periphery  of  the  root. 

This  style  of  construction  is  especially  indicated 

Tttdications.  in  two  general  classes  of  cases,  and  is  applicable  to  a. 

third,  as  follows : 


i8q 

In  pathological  conditions  where  any  extensive 
TJrst:  preparation   of  the   remaining  root,    such  as   would 

become  necessary  for  a  band,  is  precluded  because 
of  its  instability,  or  because  of  the  physical  or  nervous  condition  of  the 
patient ;  or,  where  a  recession  of  the  gum  from  the  normal  gingival  line 
would  require  the  application  of  a  crown  without  a  band  for  esthetic 
reasons. 

Where  the  decay  and  destruction  of  the  root  is 
Second:  so  extensive  as  to  preclude  the  possibility  of  apply- 

ing a  band, — in  which  conditions,  because  of  the  ex- 
treme shortness  and  consequent  close  proximity  of  the  end  of  the  root  to 
the  border  of  the  alveolus,  no  opportunity  for  securing  an  accurate  adap- 
tation of  a  band  is  afforded. 

In  this  class  of  cases  a  crown  may  be  constructed  by  sv/aging  or 
burnishing  a  base  to  a  close  conformation  with  the  surface  and  irregular 
edge  of  the  root,  with  a  degree  of  accuracy  of  adaptation,  and  support 
to  the  root  which  will  offer  a  secure  and  reasonably  permanent  attach- 
ment. 

It  is  also  quite  generally  applicable  and  more  or 

tl)ird:  less  extensively  employed  in  those  typical  cases  where 

the  root  is  sufficiently  large  and  strong,    and    free 

from  the  evidences  of  caries  or  disintegration,  as  to  probably  require  no 

support  and  protection,  such  as  the  application  of  a  band  affords. 

Also,  it  is  particularly  applicable  and  perhaps  most  often  the  desir- 
able procedure,  in  restoring  the  crowns  of  partially  developed  teeth  in 
the  mouths  of  young  patients,  because  of  thus  avoiding  any  possible  irri- 
tation to  the  more  or  less  susceptible,  sensitive  and  highly  organized  tis- 
sues in  such  cases. 

The  requirements  of  construction  constitute  se- 
KequiretncntS.  curing  a  preparation  of  the  root,  wherever  sufficient 
tooth  structure  remains,  which  will  mechanically 
prevent  subsequent  displacement  of  the  crown,  and  of  then  securing  adap- 
tation of  the  base  to  both  the  surface  and  periphery  of  the  root,  which  will 
afford  a  firm  seating,  and,  in  so  far  as  possible,  preclude  a  dissolution 
or  disintegration  of  the  cementing  medium,  or  the  subsequent  occurrence 
of  caries. 

While  a  close  observation  and  fulfillment  of  these  requirements  will 
doubtless  make  such  a  result  possible,  the  degree  of  stability  in  the  attach- 
ment will,  of  course,  depend  much,  if  not  entirely,  upon  the  dowel ;  which, 
because  of  thus  assuming  a  preponderance  of  the  stress  imposed,  must  be 
properly  adjusted  to  the  canal,  and  of  uniform  and  adequate 
rigidity. 


190 

mctDod  of  Construction. 

As  the  method  of  construction  for  this  style  of  crown  differs  only 
in  the  details  incident  to  the  preparation  of  the  root,  and  the  adaptation 
of  the  base,  all  reference  to  the  application  of  the  facing  and  the  comple- 
tion of  the  crown,  whether  for  gold  or  porcelain  work,  will  be  purposely 
avoided,  because  the  procedure  from  this  point  on  is  identical  with 
that  which  is  elsewhere  considered  in  connection  with  each. 

In  the  application  of    this    style    of    crown    to 

tvpical  6a$($.        typical   cases,   such  as  have  been  considered  in  the 

first  and  third  classes  of  indications,  and  which  will 

"be  confined  mostly  to  the  six  anterior  teeth,  the  first  essential  feature  in 

the  detail  of  construction  is  the  proper  preparation  of  the  basal  surface 

of  the  root. 

In  this  particular  the  requirements  dift'er  from 

Root  Preparation,      those  incident  to  the  band  and  dowel  crown,  in  that 

110  periplicral  triiiiiiiiiig  is  necessary,  and  that  the  end 

of  the  root  must  be  so  shaped  as  to  offer  mechanical  resistance  to  the  stress 

imposed. 

In  the  six  anterior  teeth    this    may    be    accom- 

$\K  J\nUt\9r  Ziith,    plished  by  beveling  the  root  both   labially  and  lin- 

gually  from  a  central  point,  so  that  the  plate,  which 

is  to  form  the  base  of  the  crown,  will  straddle  the  exposed  end,  thus  also 

overcoming  any  tendency  toward  a  possible  rotation  or  displacement  of 

the  crown. 

The  labial  bevel  should  usually  extend  from  tire  lingual  edge  of  the 
pulp  canal  to  a  point  sufficiently  far  beneath  the  gum  to  allow  for  the 
thickness  of  the  plate,  and  thus  admit  of  placing  the  neck  of  the  facing 
in  direct  contact  with  the  tissue,  which  adds  to  the  esthetic  effect  by 
making  the  joint  invisible. 

The  lingual  bevel  should  not  extend  quite  to  the  gum  line,  because  of 
the  absence  of  esthetic  requirements  upon  this  surface,  and  of  the  prob- 
able advantage  in  having  the  joint  exposed  to  view  to  insure  the  accuracy 
of  adaptation,  and  to  the  movements  of  the  tongue  and  action  of  the  secre- 
tions, to  render  it  more  hygienic  or  self-cleansing.      (Fig.  158a.) 

This  preparation  may  be.  easily  accomplished  with  flat-edge  carbo- 
rundum stones,  though  the  use  of  the  root  facer  will  facilitate  cutting  the 
root  below  the  gum  upon  the  labial  surface.  Wherever  enamel  is  allowed 
to  remain,  however,  and  no  band  is  employed,  this  instrument  must  be 
revolved  slowly,  and  used  with  extreme  care. 

While  a  similar  preparation  is  usually  desirable 

Bicuspids.  for  first  bicuspids,   because  they  are  also  subjected 

to  some  lateral  stress,  it  is  not  so    essential    to    the 


T9I 

second  bicuspids,  for  the  reason  that  these  teeth  usually  receive  vertical 
stress  mainly,  hence  a  flat  base,  such  as  is  indicated  in  Fig.  53,  is  all  that 
is  necessary,  if  the  size  and  adjustment  of  the  dowel  is  adequate. 

When  the  desired  preparation  has  been  secured, 
Adaptation  of  Plat?,    a  piece  of  pure  gold,  or  platinum,  as  the  requirements 
of  the  intended  construction  of  the  crown   may  in- 
dicate, about  34  to  36  gauge,  should  be  cut  a  trifle  larger  than  necessary, 
annealed,  and  burnished  to  a  perfect  adaptation  VN'ith  the  surface  of  the 
root. 

This  is  easily  accomplished  with  flat  and  round  burnishers,  and  the 
soft  rubber  tip  of  a  lead  pencil  will  also  be  found  useful.  While  the  thin- 
ness and  softness  of  either  pure  gold  or  platinum  will  admit  of  securing 
the  required  adaptation  by  burnishing,  the  same  may  also  be  accomplished 
by  a  primary  swaging,  if  preferable,  though  the  latter  method  is  more 
requisite  in  difficult  cases,  and  will  1)e  subsequently  considered. 


Fi(j.l58. 


After  securing  the  proper  adaptation  of  the 
JTdiUStment  of  Dowel,  plate,  the  canal  should  then  be  prepared  for  the  re- 
ception of  the  dowel,  and  the  latter  fitted  to  it,  when 
the  plate  should  be  replaced  in  position  and  the  opening  of  the  canal  out- 
lined in  it  with  a  round  or  oval  burnisher.     (Fig.  158  b.) 

The  plate  should  now  be  perforated  with  a  sharp-pointed  instrument 
or  plate  punch,  and  the  dowel  forced  through  the  perforation  until  well 
into  position.  While  the  close  fit  thus  secured  between  plate  and  dowel 
will  usually  sustain  their  relation  while  removing  and  soldering,  if  the 
same  is  doubtful,  the  usual  means  for  sustaining  it,  as  previously  de- 
scribed, may  be  observed. 

The  two  should  now  be  permanently  attached  v/ith  solder  and  then 
again  placed  in  position  on  the  root  and  reburnished,  when  the  surplus 
may  be  trimmed   away   and  the  plate   reinforced  to  prevent  a  possible 


192 

change  of  form  while  taking  the  impression,  and  subsequently  detaching 
from  the  model.     (Fig.  158  C.) 

When  the  plate  is  of  gold,  this  reinforcement  should  be  made  by  flow- 
ing a  thin  layer  of  20  karat  solder  over  the  surface  and  around  the  dowel, 
while  if  a  platinum  plate  has  been  used,  and  a  porcelain  crown  is  to  be 
made,  twenty-five  per  cent  platinum  solder,  or  pure  gold,  may  be  em- 
ployed. 

The  usual  "bite"  and  impression  should  now  be  taken  and  models 
secured,  when  the  facing  should  be  selected  and  ground  to  a  perfect  joint 
with  the  labial  and  cervical  aspect  of  the  plate,  if  it  is  to  be  backed  up  and 
finished  with  gold  (Fig.  158  d),  and  the  crown  then  completed  in  the 
usual  manner,  and  finished  and  mounted.     (Fig.  158  e.) 

Extensive  Destruction  of  Root. 

In  that  class  of  cases  where  the  root  has  been  more  or  less  extensively 
destroyed  from  disintegration,  or  accident,  and  presents  a  concave  sur- 


a 


Fic^.  159.  c 

h 

face  and  frail  and  irregular  edges  so  deeply  imbedded  beneath  the  gum 
as  to  preclude  the  adaptation  of  a  band,  and  yet  possessing  sufficient 
stability  and  integrity  to  afford  a  reasonably  firm  attachment  for  a  well- 
adapted  crown,  as  has  been  mentioned  in  the  second  class  of  indications, 
the  first  essential  procedure  incident  to  the  construction  of  the  crown  is 
to  tightly  press  away  the  surrounding  soft  tissue  with  temporary  stopping, 
or  gutta  percha,  until  a  free  exposure  of  the  end  of  the  root  is  obtained. 

While  this  may  require  two  or  three  sittings,  repeating  the  proce- 
dure at  each,  such  time  will  be  found  to  have  been  well  expended,  when 
it  is  desirable  to  make  an  effort  to  successfully  crown  such  teeth,  because 
•of  thus  making  possible  and  facilitating  the  accurate  adaptation  of  the 
plate  to  the  root,  and  the  subsequent  permanent  attachment  of  the  finished 
crown. 

When  the  root  has  been  thus  freely  exposed,  the  irregular  edges 
should  be  ground  down  with  small  stones,  or  root  facer,  until  as  smooth 


193 

and  even  as  possible  ;  and  all  decay  then  removed,  after  which  the  re- 
maining root  should  be  thoroughly  disinfected  and  sterilized,  in  order  to 
arrest  any  further  progress  of  caries. 

The  best  means  of  obtaining  the  correct  adaptation  of  the  plate  to 
the  root  will  depend  much  upon  the  condition  presenting,  and  while  the 
required  conformation  may  often  be  obtained  by  burnishing,  a  more  cer- 
tain, and  perhaps  increased,  accuracy  will  not  infrequentlv  be  secured  by 
swaging. 

To    accomplish    the    swaging,     whenever     such 

Swaging  Plate.        procedure   may  be  indicated,   or  seem  desirable,  an 

accurate  and  well-defined  impression  of  the  edge  and 

surface  of  the  root  must  be  taken,  and  fusible  alloy  dies  m_ade  therefrom. 

The  use  of  pink  base-plate  gutta  percha  affords 
Impression  of  Roof,     the  most  simple  and  accurate  means  of  obtaining  a 
well-defined  impression  of  the  end  of  the  root. 
In  the  procedure  this  should  be  cut  into  moderately  small  pieces  and 
carefully  and  slowly  warmed,  on  a  mica  slab  over  a  flame,  or  on  the  elec- 
tric annealer,  until  it  is  plastic,  when  a  quantity  sufficient  to  fill  the  spac^ 
to  be  occupied  by  the  crown  should  be  tightly  packed  with  burnishers 
over  and  against  the  end  of  the  root,  and  in  between  the  adjacent  teeth 
if  any  be  present. 

Care  should  be  observed  to  avoid  over-heating  or  bu~ning  the  gutta 
percha,  as  such  accident  entirely  destroys  its  manipulative  qualities.  ^ 

This  should  now  be  chilled  with  a  spray  of  cold  water,  and  removed 
(Fig.  159  a),  and  when  sufficiently  accurate,  fusible  alloy  dies  mav  be 
obtained  from  it.  '  ' 

To  obtain  the  dies,  the  impression  should  be  in- 
DIC$,  vested,  with  the  imprint  of  the  root  downward,  in  a 

base  of  plaster  of  proportions  sufficient  to  be  subse- 
quently trimmed  to  admit  of  the  adjustment  of  the  rubber  casting  ring 
(Fig.  159  b).  When  the  plaster  has  become  thoroughlv  crystallized,  and 
has  been  thus  trimmed,  it  should  be  placed  over  a  small'flame  and  allowed 
to  heat  slowly  until  the  gutta  percha  may  be  removed  (Fig.  159  c),  when 
the  rubber  ring  should  be  adjusted,  and  the  die,  and  subsequently  the 
counter-die,  secured  with  fusible  alloy. 

Pure  gold  or  pure  platinum,  as  the  requirements  may  indicate    of 
the  thickness  of  about  36  gauge,  should  be  now  annealed,  and  swaged 
after  which  it  may  be  further  adapted  to  the  root  by  burnishing,  as  al- 
ready indicated,  and  the  dowel,  or  dowels,  then  adjusted  and  soldered. 

The  length  and  size  of  the  canal,  or  canals,  in 

Dowels  such  roots  will  indicate  whether  one  or  two  dowels 

should  be  used,  and    as    they    are    generally    much 


194 

shorter  than  usual,  and  the  major  portion  of  the  strength  of  the  attach- 
ment will  depend  upon  the  dowel,  it  is  essential  that  it  should  be  of  ade- 
quate size  and  length  to  thoroughly  fill  the  canal;  hence  the  use  of  two, 
whether  they  may  be  separate  from  each  other,  or  in  contact  and  subse- 
quently united  with  solder,  is  frequently  required. 

The  relation  between  the  plate  and  dowel,  or  dowels,  should  be  tem- 
porarily secured  in  the  manner  indicated,  and  then  permanently  sustained 
by  soldering,  and  wherever  two  dowels  are  used,  and  particularly  when 
they  are  separated,  an  investment  should  invariably  be  employed. 

When  they  have  been  soldered,  the  cap  should  be  placed  upon  the 
root  and  the  edge  of  the  plate  readapted  by  burnishing,  in  which  the  use 
of  a  smooth  foot  plugger  in  the  automatic  mallet  will  often  be  found  ad- 
vantageous. 

The  usual  "bite"  and  impression  should  be  then  taken  and  the  crown 
completed  as  the  requirements  may  indicate,  as  illustrated  in  Fig.  i6o. 

While  the  interior  of  such  roots  is  sometimes  previously  filled  with 
cement  or  amalgam,  and  the  plate  then  adapted  to  this  surface  by  burnish- 


Ficj.  160. 


ing,  the  increased  accuracy  obtained  by  swaging  it  to  closely  follow  the 
concaved  surface  of  the  root,  and  the  additional  support  thus  rendered  to 
the  latter  with  a  minimum  quantity  of  cement,  adds  materially  to  the  in- 
tegrity of  the  attachment  between  the  two,  when  subsequently  mounted. 

In  instances  where  it  may  become  necessary  to 

Construction  construct  the  crown  upon  models,   the  most  useful 

Upon  Models.  and  accurate  reproduction  of  the  conditions  may  be 
secured  by  first  fitting  a  wooden  dowel  into  the  canal 
and  then  packing  gutta  percha  over  and  around  it,  until  the  impression 
of  the  end  of  the  root  has  been  obtained,  as  indicated. 

When  the  desired  degree  of  accuracy  has  been  thus  secured,  it 
should  be  placed  in  position,  and  a  plaster  impression  then  taken  over  it. 
The  removal  of  the  latter  will  usually  bring  the  gutta  percha  with  it,  but 
if  not,  it  should  be  detached  from  the  root  and  placed  in  its  proper  posi- 
tion in  the  impression. 

When  this  has  become  thoroughly  dry,  the  open  ends  may  then  be 
closed  up  with  mouldine,  and  the  impression  filled  with  fusible  alloy. 


195 

After  separating  from  the  plaster,  and  detaching  the  gutta  percha 
and  wooden  dowel,  this  procedure  will  result  in  a  metal  model  with  a 
more  or  less  perfect  reproduction  of  the  root  and  its  canal,  upon  which 
opportunity  is  afforded  for  the  construction  of  the  crown  in  the  manner 
indicated,  and  with  reasonable  accuracy. 

[The  application  of  this  st}le  of  crown  to  the  molar  teeth  is  perhaps 
confined  more  especially  to  porcelain  work,  but  the  same  general  princi- 
ples should  be  observed  irrespective  of  the  style  of  construction.] 


Jfpplication  «f  Dowel  erown$  mitbout  Plate  or  Bind. 


CHAPTER  XL 

Advantages ;    Disadvantages ;    Indications ;    Requirements ;    Various    Designs ;    Sep- 
arable    Dowels,     Inseparable     Dowels,    Comparative    Advantages.     The    Davis 
Crown :      Application,    Mounting,   Repairing,    With   Band   and   Cap ;    Accu- 
racy  of  Adaptation   Without   Band.    The  Logan  Crown :     Comparative 
Advantages  and  Disadvantages  ;  Application  ;  Mounting.  With  Band 
and  Cap.     Advantages ;  Procedure.       Variation     of     Methods : 
Substituting  Separate  Dowel ;    Procedure.      Increased    Ac- 
curacy of  Adaptation,   Procedure.       Porcelain     Work. 
The  Brewster  Crown :    Application.     The  "Fellow- 
ship" Crown :     Application.     Repairing.     Tube 
Crowns :      Application ;    Procedure.     Tem- 
porary Crowns  :    Indications ;  Proced- 
ure ;   Use  of  Amalgam ;     Use     of 
Vulcanite. 


The  various  styles  of  ready-made  porcelain  crowns  which  are 
designed  to  be  adapted  directly  to  the  root,  without  the  employment 
of  a  band  or  plate,  and  attached  by  means  of  a  dowel,  which  may  be 
either  a  separable  or  inseparable  part  of  the  crown,  will,  in  regular 
sequence,  be  designated  and  considered  under  this  classification. 

While  almost  any  of  the  several  designs  of  this  particular  style  of 
crown  may  be  adapted  with  a  band  and  cap,  or  even  with  a  simple  plate, 
they  are  thus  classified  because  of  being  usually  employed  without  such 
addition,  and  of  being  originally  designed  to  be  so  adapted. 

Although  this  particular  style  of  crown  preceded  all  others  designed 
especially  for  the  anterior  teeth,  they  are  still  used  somewhat  extensively, 
and,  irrespective  of  the  improved  means  for  obtaining  greater  integrity 
and  permanency,  they  doubtless  possess  some  intrinsic  advantages,  and 
still  occupy  a  more  or  less  limited  sphere  of  usefulness  and  serviceability. 

Previous  to  the  individual  construction  of  porce- 

HdVtintagCS.  Iain-faced  crowns,  the  application  of  porcelain  work, 

and  the  present  facilities  for  securing  a  more  per- 
fect adaptation  to  the  root  with  equal  opportunities  for  observing  the 
esthetic  requirements,  as  indicated  in  the  preceding  chapter,  the  advan- 
tages possessed  by  this  style  of  crown  were  particularly  desirable. 

These  constituted  the  ease  with  which  the  finished  crown  might  be 
procured ;  the  absence  of  the  necessity  for  removing  the  enamel  from 


197 

the  periphery  of  the  root ;  the  facility  and  dispatch  with  which  they  might 
be  adapted,  and  the  natural  and  translucent  appearance  which  the  splendid 
forms  and  colors  of  some  makes  afforded. 

While  the  latter  is  always  an  eminently  desirable  feature,  particu- 
larly in  the  restoration  of  the  six  anterior  teeth,  and  gives  to  all  porce- 
lain crowns  of  any  similar  design  a  distinctive  advantage  over  those  in 
which  the  translucency  is  destroyed  by  the  presence  of  a  backing,  the 
former  should  be  so  considered  in  the  application  of  crowns  designed 
to  serve  as  permanent  reproductions,  only  when  such  are  especially  indi- 
cated, and  as  a  means  of  expediency. 

The   principal   features   which   may   be   reason- 

Disadvantaflts.  ably  regarded  as  disadvantages,  when  such  crowns 
are  adapted  without  band  or  plate,  lie  in  the  diffi- 
culty of  obtaining  a  crown  of  the  same  diameter  as  the  root,  and  of  se- 
curing a  continuous  and  practically  impervious  joint  between  it  and  both 
the  base  and  periphery  of  the  root,  together  with  the  resultant  absence 
of  preventive  means  and  prophylactic  measures  against  the  subsequent 
dissolution  or  disintegration  of  the  cementing  medium  from  the  pene- 
tration of  saliva,  and  the  destruction  of  the  root  by  caries  or  fracture. 

As  the  result  of  a  failure  to  observe  the  higher  requirements  in 
this  connection,  many  roots  have  been  lost  from  caries,  or  fracture,  which 
might  otherwise  have  possessed  greater  integrity  and  usefulness;  and  it  is 
by  no  means  uncommon  to  see  such  crowns  so  displaced  from  the  stress 
of  mastication,  and  the  inherent  weakness  of  the  dowel,  as  to  effect  a 
disarrangement  of  the  alignment,  and  afiford  a  pocket  between  crown 
and  root  which  serves  as  a  receptacle  for  the  accumulation  of  the  products 
of  decomposition. 

In  consequence  of  these  possible  disadvantages 

Indications.  the  application  of   such  crowns  without  a  band  or 

plate,  or  without  observing  some  means  of  securing 
a  more  perfect  and  impervious  joint  than  can  usually  be  obtained  by 
grinding  one  surface  to  fit,  and  approximate  with,  another,  is  usually 
indicated  only  in  those  cases  where  expediency  renders  such  choice  abso- 
lutely necessary;  or  where,  from  the  instability  of  the  root,  a  recession  of 
the  gum  tissue,  or  other  pathological  conditions,  or  for  pecuniary  reasons 
the  application  of  a  crown  affording  greater  stability  in  the  attachment, 
or  greater  protection  to  the  root,  may  not  seem  warrantable. 

And  even  in  such  instances  their  application  should  usually  be  con- 
fined to  the  six  anterior  teeth,  because  of  the  increased  difficulty  or- 
dinarily encountered  in  adjusting  them  to  the  more  or  less  irregular 
shapes  and  uncertain  canals  of  the  bicuspids  and  molars. 


Conscientiously  considered,  such  crowns  must  usually  be  regarded  as 
Icinporary  work,  in  view  of  the  reasonable  opportunities  for  securing 
greater  permanency. 

Kequiremetits. 

In  the  application  of  any  of  the  various  designs  now  used,  the  same 
esthetic  requirements  as  indicated  in  the  preceding  chapter  prevail,  and 
the  possible  permanency  of  the  crowns  will  naturally  increase  in  proportion 
to  the  degree  of  accuracy  obtained  in  adapting  them  to  a  close  approx- 
imation with  both  the  base  and  peripheral  outline  of  the  root :  and  much 
of  the  success  attending  such  an  adaptation  will  depend  upon  the  proper 
root  preparation. 

In  the  preparation  of  the  root  for  the  reception 
Root  Preparation.      of  such  crowns,  the  removal  of  enamel,  or  peripheral 
preparation  of  any  kind,  becomes  entirely  unneces- 
sary, of  course,  but  the   shape  given  to  the  1)asal  surface  should  differ 


Ficj.161. 

from  that  indicated  for  the  plate  and  dowel  crown,  because  of  the  in- 
creased difficulty  of  securing  an  adaptation  to  such  a  shape,  hy  grinding. 

With  the  exception  of  the  peripheral  trimming,  the  preparation  pre- 
viously indicated  in  Fig.  50  will  be  found  the  most  favorable  to  the  re- 
Cjuirements  of  the  crown,  and  to  the  facility  and  accuracy  with  which  the 
adaptation  may  be  secured. 

This  consists  in  grinding  the  labial  edge  just  beneath  the  gingival 
line,  and  in  allowing  the  lingual  to  project  slightly  beyond  it,  with  the 
basal  surface  assuming  a  smooth  inclined  plane.     (Fig.  161.) 

The  former  admits  of  the  advantages  considered  in  this  connection 
in  the  preceding  chapter,  while  the  latter  greatly  facilitates  the  opportuni- 
ties for  securing  the  desired  and  required  adaptation  of  the  crown  to 
the  root. 


199 

Uarious  De$idn$. 

Although  numerous  designs  of  lliis  style  of  crown  have  been  pre- 
sented from  time  to  time,  as  previously  recorded,  only  those  which  are 
now  manufactured  in  good  variety,  and  which  are  more  or  less  extensively 
employed,  will  be  considered.  Jn  their  consideration  it  becomes  necessary 
to  divide  them  into  two  classes,  because  of  the  variation  in  their  con- 
struction, and  in  the  details  incident  to  their  respective  application.  Such 
variation  mainly  depends  upon  the  possession  of  separable  or  inseparahle 
dowels,  and  causes  them  to  be  classified  accordingly. 

The  feature  of  this  class  of  crowns  embraces  a 

Separable  Dowels,      separable  or  removable  dowel,  which  may  be  i)revi- 

ously  mounted  in  the  root,  and  to  the  projecting  end 

of  which  the  crown  may  be  subsequently  attached.     They  are  designed 

for  the  purpose  of  facilitating  the  adaptation  of  the  crown  to  the  root, 

and  include  the  principles  of  the  Davis  crown. 

This    class    of    crowns     embraces     the    feature 
Inseparable  Dowels,     of  an  inseparable  dowel,  which  is  baked  in  or  other- 
wise securely  attached  to,  the  porcelain,  and  forms 
an  integral  part  of  the  crown,  such  as  the  Logan,  Brewster  and  "Fellow- 
ship" designs. 

/r*^^*«,«„.  While  both  of  these  stvles,  and  all  of  these  re- 

Gomparatipc  .■  ,         .  ,  ,         , 

JIdfantafles.  spective   makes   of   crowns,    are    much    used    at   the 

present  time,  and  either  is  capable  of  being  more  or 
less  readily  adjusted  to  the  root,  a  close  study  and  analysis  of  the  com- 
parative advantages  of  the  two  classes  must  result  in  favor  of  those  pos- 
sessing a  separable  or  removable  dowel,  providing,  of  course,  that  ade- 
quate means  are  afforded  for  the  subsequent  attachment  of  the  crown. 

This  is  apparent,  for  the  reason  that  the  opportunities  for  securing 
the  closest  possible  adaptation,  by  grinding,  are  greatly  facilitated  by  the 
temporary  absence  of  the  dowel,  as  its  presence  must  necessarily  afford 
some  obstruction  to  this  procedure,  and  at  least  increase  the  difficulties 
attending  it,  together  with  the  liability  of  weakening  the  dowel,  l)y 
grinding  it,  during  the  process. 

Cbe  Davis  £rowti. 

Of  the  several  designs  of  crowns  possessing  separable  dowels,  the 
Davis  crown,  suggested  by  Dr.  Chas.  H.  Davis,  and  manufactured  by 
the  Consolidated  Dental  ^danufacturing  Co.,  is  the  only  one  which  is 
now  employed  to  any  extent,  or  which  is  made  in  a  sufftcient  variety  of 
moulds  and  colors  to  meet  the  requirements,  and  it  has  quite  an  exten- 
sive application. 

It  is  an   all   porcelain  crown,  having    a    slightly    concaved    base, 


200 

in  the  center  of  which  is  a  depressed  rim,  which  affords  a  rest  for  the 
shoulder  on  the  dowel,  and  a  countersunk  cavity  extending  into  the 
crown  sufficiently  deep  to  accommodate  the  projecting  end  of  the  dowel. 

The  dowel  is  proportionate  with  the  size  of  the  crown ;  slightly 
tapered ;  corrugated  throughout  its  entire  length  to  afford  increased  at- 
tachment to  the  cementing  medium ;  has  one  flattened  side  to  prevent  the 
possibility  of  rotation,  and  a  shoulder  which  adapts  itself  to  the  depressed 
rim  for  its  accommodation  in  the  crown,  and  is  made  of  German  silver 
alloy  for  the  purpose  of  obtaining  greater  inherent  strength  and  rigidity 
than  is  possessed  by  platinum.     (Fig.  162.) 

When  the  proper  selection  has  been  made,  the 

Jlpplication.  primary    rough    grinding    may    be    done    upon    the 

model    if    the    outline    of    the    root    is     sufficiently 

accurate,  but  the  final   adjustment  to  the  desired  adaptation  should  be 


Fiq.l62. 


Fiq.163. 


made  directly  upon  the  root  itself.  This  should  be  accomplished  with 
carborundum  stones  in  the  engine,  and  when  sufficiently  accurate  the 
ground  surfaces,  excepting  the  base,  should  be  then  nicely  polished  with 
disks. 

The  canal  should  now  be  prepared  for  the  reception  of  the  dowel, 
and  the  latter  fitted  closely  to  it;  in  some  roots  it  may  become  necessary 
to  shorten  it  somewhat  from  the  apical  end.  When  thus  primarily  fitted, 
it  should  be  placed  in  position  in  the  crown  and  temporarily  sustained 
with  wax  until  the  two  may  be  adjusted  to  position  on  the  root.  (Fig. 
163,  A.)  This  may  necessitate  a  slight  enlargement  of  the  basal  portion 
of  the  canal,  or  possibly  the  bending  of  the  dowel,  until  the  adjustment  of 
the  crown  to  its  proper  relation  with  the  root  is  obtained,  after  which 
the  crown  and  dowel  may  be  permanently  mounted.     (Fig.  163,  B.) 


201 

In  mounting,  all  particles    of    wax    should    be 

mounting.  thoroughly  removed  from  the  crown  and  dowel,  and 

the  root  rendered  aseptic  and  dry,  when  the  attach- 
ment of  the  latter  to  both  crown  and  root  may  be  made  simultaneously 
with  cement,  or  if  it  is  preferable  to  use  gutta  percha,  the  dowel  should 
be  first  fixed  in  the  crown  with  cement,  and  attachment  to  the  root  made 
with  gutta  percha. 

One  of  the  most  important  advantages  possessed 
Repairing.  by  this  style  of  crown  is  the  ease  and  facility  with 

which  repair  may  be  effected  in  the  event  of  subse- 
quent fracture. 

In  such  instances  the  dowel  need  not  usually  be  disturbed,  as  its  pro- 
jecting end  will  afford  ample  opportunity  for  the  retention  of  a  new 
crown,  after  the  removal  of  the  remaining  cement,  and  the  necessary 
adaptation  has  been  secured  by  grinding.  These  crowns  may  also  often  be 
found  applicable  and  useful  in  the  repair  of  the  Logan,  and  other  styles 
of  crowns,  where  no  backing  is  used,  and  the  projecting  end  of  the  dowel 
remains  sufficiently  long  to  afford  adequate  retention  and  resistance. 

When   it   may   seem   desirable    to    employ    the 
iUitb  Band  and  Cap.     band  and  cap,  in  the  adaptation  of  this  crown,  and 
thus   add  to  its   possible  permanency  by   supplying 
means  for  the  protection  of  the  root,  it  may  be  accomplished  with  ease. 

In  their  application  in  conjunction  with  band  and  cap,  the  root 
should  be  prepared  and  the  band  fitted  in  exact  accordance  with  the  prin- 
ciples previously  outlined  in  connection  with  the  band  and  dozvel  croivn. 

When  the  band  has  been  thus  fitted  and  trimmed  to  the  proper  width, 
and  the  root  ground  down  to  evenly  approximate  its  edge,  as  indicated  in 
Fig.  125,  B,  the  crown  should  be  selected  and  ground  to  a  close  confor- 
mation with  the  basal  surface  of  the  root,  as  well  as  its  peripheral  outline. 

The  dowel  should  then  be  temporarily  adjusted  to  the  crown  and 
fitted  to  the  canal,  until  the  crown  may  assume  its  proper  relation.  A 
plate  of  pure  gold,  32  gauge,  should  now  be  perforated  for  the  dowel, 
placed  in  position  on  the  crown,  and  trimmed  to  follow  its  outline,  with 
an  allowance  of  about  1/32  of  an  inch  surplus  around  the  entire  circum- 
ference. 

After  annealing  this  plate,  it  should  be  again  placed  in  position  on 
the  crown,  and  both  adjusted  to  the  root,  with  the  band  in  place.  A  de- 
gree of  accuracy  in  the  adaptation  of  the  plate  to  the  root,  crown,  and 
edge  of  the  band  may  be  obtained  by  placing  a  piece  of  soft  wood  against 
the  end  of  the  crown,  and  gently  tapping  it  with  a  mallet,  and  then  hold- 
ing firmly  andi  burnishing  the  surplus  edge  of  the  pure  gold  plate  np 
tight  against  the  band. 


202 


When  this  has  been  accompHshed,  the  crown  should  be  removea, 
and  the  pure  gold  plate  placed  in  its  proper  relation  to  the  band,  which 
has  been  made  possible  by  the  burnishing  of  this  surplus  edge,  and  the 
two  then  united  with  20  karat  solder. 

When  the  cap  has  been  formed  by  the  union  of  the  band  and  plate, 
and  the  surplus  and  excess  edge  finished  down  smooth  with  stones  and 
disks,  it  should  be  adjusted  to  position  on  the  crown  (to  which  the  dowel 
still  remains  temporarily  attached)  and  securely  united  with  wax. 

The  interior  of  the  cap  should  now  be  filled  with  investment  ma- 
terial, or  plaster,  as  indicated  in  Fig.  127,  in  order  to  securely  sustain 
their  relation  while  soldering.  After  this  has  become  sufficiently  hard- 
ened, the  crown  may  be  easily  detached  by  slightly  heating  it  over  a  flame 
until  the  wax  melts,  when  the  dowel  should  be  united  to  the  cap  by  filling 
in  the  space  around  the  shoulder  with  20  karat  solder. 

The  cap  may  now  be  finished  and  polished,  and  then  permanently 
attached    to    the    root,    when     the    crown    may    be     ])laced     in     posi- 


Ficj .  164: 


tion,  and  if  too  long,  because  of  the  thickness  of  the  pure  gold  between 
it  and  the  root,  the  incisal  end  should  be  ground  until  the  length  is  cor- 
rect and   the  crown   then    subsequently   mounted    with   cement.        (Fig. 

164.) 

While  the  floor  may  be  attached  to  the  band  in  the  ordinary  man- 
ner, without  observing  this  detail,  and  the  proper  relation  between  the 
parts  subsequently  secured,  tnis  procedure  is  warrantable  and  preferable 
because  of  the  accuracy  and  the  conservation  of  tooth  structure  thus  ob- 
tained, as  otherwise  the  canal  may  need  to  be  much  enlarged  to  admit  of 
placing  the  crown  in  its  proper  position  and  relation. 

A  method  of    securing    a    preservation    of    the 
JlCCUracy  of  Jldaptation  root,  and  a  degree  of  accuracy  in  the  adaptation  of 

UlitbOUt  Band.         these  crowns,  without  a  band  or  cap,  which  seems 
quite  practical  and  applicable  to    many    cases,    has 
been  suggested  by  Dr.  J.  R.  Owens,  of  Cleveland,  Ohio. 


203 

In  this  method  the  basal  end  of  the  canal  is  enlarged  as  much  as  is 
consistent  with  the  strength  of  the  remaining  edge  of  the  root,  and  then 
somewhat  countersunk.     (Fig.  165,  A.) 

The  crown  is  then  adjusted  to  its  proper  adaptation  by  grinding,  and 
the  dowel  subsequently  fitted  until  admitting  of  the  correct  adjustment 
of  the  crown,  when  the  dowel  should  be  mounted  in  the  constricted  por- 
tion of  the  canal  with  cement. 

The  surplus  cement  flowing  into  the  countersunk  cavity  should  be 
removed  and  the  latter  then  filled  with  amalgam.  (Fig.  165,  B.)  While 
this  remains  plastic,  the  crown  should  be  placed  in  position  and  gently 
forced  to  its  proper  adaptation  with  a  piece  of  soft  wood  and  small 
mallet.  The  excess  amalgam  is  then  trimmed  away,  until  a  smooth  joint 
between  crown  and  root  remains,  when  the  crown  should  be  gently  re- 
moved and  afterward  permanently  attached  with  cement.     (Fig.  165,  C.) 

The  advantages  claimed  for  this  method  are  the  protection  afforded 


to  the  end  of  the  root  by  the  amalgam,  and  the  accuracy  of  the  adapta- 
tion between  crown  and  root  which  is  facilitated  by  its  manipulation  while 
in  the  plastic  state.  Its  application,  however,  is  necessarily  confined  to 
good,  strong  roots,  and  while  the  How  ''screw-post"  is  used  by  the 
advocate,  as  illustrated,  the  dowel  of  the  Davis  crown  will  doubtless 
answer  as  well. 

Cbe  Lmn  £rown. 

Of  the  various  crowns  with  fixed,  or  inseparable  dowels,  the  Logan 
crown,  originally  designed  by  Dr.  M.  L.  Logan,  and  manufactured  by 
the  S.  S.  White  Dental  Mfg.  Co.,  is,  because  of  the  almost  unlimited 
variety  of  splendid  forms  and  colors  in  which  it  is  made,  probably  the 
most  generally  employed  and  universally  adaptable. 

The  crown  is  made  with  a  slight  groove  or  depression  in  its  base, 
immediately  surrounding  the  dowel,  thus  forming  an  elevated  rim 
around  the  edge  which  facilitates  the  adaptation,  and,  when  not  entirely 


204 

obliterated  by  grinding,  affords  increased  strength  to  the  attachment  by 
.  admitting  of  the  presence  of  a  greater  quantity  of  the  mounting  material. 
The  dowel  is  of  platinum  and  is  baked  into  the  body  of  the  crown. 
It  is  flattened  and  tapering  in  shape,  and  adjusted  in  the  crown  with  the 
greatest  diameter  placed  labio  and  hucco-lingually,  or  in  line  with  the 
direction  in  which  the  greatest  stress  is  usually  imposed ;  and  a  slight 
corrugated  depression  in  each  side  aids  the  attachment  of  the  mounting 
material.     (Fig.  i66.) 

While  this  form  of  dowel  is  based  upon  theo- 
ComparatiPC  retically  scientific  principles,   objectionable  features 

Jfdl)dntade$  and  of  some  importance  contra-indicate  its  too  general 
Di$adt)(inta9C$.  application,  and  detract  from  its  practicability. 
These  constitute  the  possible  weakening  of  small 
roots  by  the  enlargement  of  their  canals  to  the  extent  necessary  to  ac- 
commodate the  greatest  diameter  of  the  dowel ;  the  possibility  of  its 
bending  under  the  application  of  stress  in  the  line  of  its  smallest  diameter, 
and  the  inherent  weakness  of  a  platinwn  dowel  which  is   further   an- 


/vy.  166. 

nealed  to  its  softest  form  by  being  subjected  to  the  high  degree  of  heat 
necessary  to  fuse  the  porcelain. 

In  many  cases  this  required  destruction  of  the  root  may  leave  it 
so  weakened  as  to  be  more  or  less  easily  fractured,  if  no  band  is  em- 
ployed, which  is  not  an  uncommon  occurrence ;  and  the  lack  of  rigidity 
in  the  dowel,  particularly  in  its  lateral  dimensions,  affords  opportunity 
for  it  to  bend  under  stress  in  this  direction,  and  thus  admit  of  the  dis- 
placement of  the  crown,  which  tendency  or  possibility  may  not  always 
be  overcome  by  the  close  approximation  of  the  crown  to  the  adjacent 
teeth. 

In  such  cases,  and  especially  where  the  latter  is  not  possible,  un- 
less extreme  care  be  taken,  the  employment  of  a  crown  possessing  such 
a  dowel  may  be  contraindicated,  and  the  application  of  one  with  a  more 
round  and  rigid  dowel  may  be  found  more  serviceable. 

In  the  application  of  the  Logan  crown  the  root 

Jlpplicati^n.  should  be  prepared,  a  model  secured,  and  the  selec- 

tion made  in  accordance  with  the  previously  men- 
tioned requirements  for  this  general  style  of  crown. 


205 

A'  more  accurate  selection  of  the  crown  for  the  individual  case  may 
be  greatly  facilitated  by  preparing  the  canal  after  shaping  the  root,  and 
then  adjusting  a  temporary  dowel  of  wood  or  metal,  allowing  it  to' pass 
well  into  the  canal  and  to  extend  down  to,  or  near,  the  incisal  end  of 
the  adjacent  teeth.  (Fig.  167.)  The  end  of  an  ordinary  wooden  tooth- 
pick will  answer  this  purpose  nicely,  and  when  so  adjusted,  a  modeling 


Ficj.  167. 

compound  impression  should  be  taken  with  it  in  position. 

In  removing  the  impression,  the  temporary  dowel  should  remain 
firmly  embedded  in  it,  or  be  subsequently  so  placed,  and  the  model  made. 

The  removal  of  the  dowel  from  the  model  will  leave  an  outline  of 
the  canal,  and  indicate  its  size,  and  position,  in  relation  to  the  root,  all 
of  which  will  be  found  decidedly  convenient  in,  and  advantageous  to, 
the  selection  of  the  crown,  because  of  the  facility  with  which  it  may  be 
readily  adjusted  to  place.     (Fig.  168.) 


Ficj.  168. 

While  the  final  adaptation  of  the  crown  should  always  be  made  di- 
rectly upon  the  root,  the  above  procedure  will  be  found  additionally  ad- 
vantageous if  the  impression  is  taken  in  plaster,  and,  after  drying  thor- 
oughly, then  filled  with  fusible  alloy.  This  affords  an  accurate  and 
comparatively  indestructible  model  containing  the  outline  of  the  base  of 
the  root,  and  a  reproduction  of  the  canal ;  and  the  crown  may  be  selected, 


206 

and  primarily  ground  to  a  fairly  accurate  adjustment  upon  it,  during  the 
absence  of  the  patient. 

The  grinding  to  the  proper  adaptation  should  be  accomplished  with 
small  flat-edge  carborundum,  stones,  in  the  engine,  and  care  must  be 
observed  to  avoid  cutting  into  the  dowel,  or  weakening  its  attachment 
to  the  porcelain.     (Fig.  169.)     The  use  of  curved  stones,  suggested  by 


/yy  .  169, 

Mr.  Robert  Brewster,  will  be  subsequently  mentioned  (Page  214)  and 
may  be  found  useful. 

In  the  final  adaptation  of  the  crown,  the  use  of  small  disks  of  carbon 
paper,  perforated  so  as  to  slip  over  the  dowel  and  rest  against  the  base, 
with  the  carbon  side  placed  next  to  the  porcelain,  will  be  found  service- 
able in  securing  a  close  approximation.     (Fig.  170.) 

In  the  use  of  such  disks,  as  the  crown  is  pressed  to  place,  the  points 
of  contact  between  it  and  the  root  will  be  designated  by  a  black  mark 


on  the  porcelain,  and  the  grinding  at  such  points  should  be  continued 
until  the  entire  base  thus  indicates  a  uniform  contact. 

The  requirements  of  peripheral  approximation  and  occlusion  should 
now  be  observed  with  care  not  to  destroy  the  integrity  between  crown 
and  dowel,  and  when  the  adaptation  has  been  completed,  any  surfaces 
of  the  porcelain  which  have  been  ground,  excepting  the  base,  should 
be  nicely  smoothed  and  polished  with  disks,  and  the  crown  then 
mounted. 


207 

While  many  methods  of  mounting  this  style  of 
mounting.  crown  arc  advocated,  and  the  subject  in  general  will 

receive  subsequent  consideration,  the  permanency  of 
the  attachment  by  any  method  will,  of  course,  depend  much  upon  the 
accuracy  of  the  adaptation.  Where  the  joint  is  close  enough  to  be  ren- 
dered practically  impervious,  either  cement  or  gutta  percha  may  be 
used,  as  is  the  practice,  and  at  the  discretion  of  the  operator. 

The  indications  for  the  use  of  gutta  percha  increase,  however,  in 
proportion  to  the  inaccuracy  of  the  adaptation,  and  the  two  materials 
may  be  combined  to  advantage  if  desirable.  In  this  procedure  a  disk 
of  the  ordinary  pink  base-plate  gutta  percha  should  be  cut  a  trifle  larger 
than  the  base  of  the  crown,  and  then  perforated  to  slip  over  the  dowel. 
The  latter  should  now  be  slightly  roughened  with  a  sharp  instrument, 
and  both  it  and  the  base  of  the  crown  then  moistened  with  oil  of  cajaput 
or  any  solvent,  and  the  gutta  percha  disk  adjusted  to  position. 

It  should  then  be  placed  on  the  electric  gold  annealer,  or  on  a  mica 

slab,^  over  a  flame,  and  slowly  heated  until  the  gutta  percha  becomes 

plastic,  when,  after  moistening  the  root  with  water  to  prevent  adhesion, 

-the  crown  may  be  forced  to  place  with  enough  pressure  to  mould  the 

gutta  percha  to  it,  and  to  the  root,  and  to  fill  the  intervening  space. 

While  the  crown  is  now  held  firmly  in  place,  the  surplus  should  be 
trimmed  away  around  the  joint  with  a  sharp,  warm  instrument,  after 
which  it  should  be  removed  and  again  placed  upon  the  heating  apparatus, 
until  the  root  has  been  dried,  and  the  base  then  moistened  with  the 
solvent,  when  it  may  be  mounted  with  cement  in  the  ordinary  manner. 
A  similar  procedure  is  indicated  in  the  use  of  gutta  percha  alone. 

(Uitb  Bana  and  eap. 

Several  methods  of  employing  the  Logan  crown  in  combination  with 
a  band  and  cap  have  been  suggested  as  a  means  of  obtaining  greater 
permanency  in  their  application ;  and  when  so  adapted  this  or  almost  any 
of  the  various  forms  of  such  crowns  possesses  advantages  which  place 
them  next  in  rank  to  porcelain  work. 

Such   advantages   constitute   not  only   the   in- 
Mvmtum,  creased  integrity  of  the  attachment,  and  preserva- 

tion of  the  root,  but  include  the  esthetic  possibilities 
which  may  be  obtained  in  the  translucent  and  natural  appearance  af- 
forded by  an  all  porcelain  crown  devoid  of  the  presence  of  any  backing. 

Of  the  several  methods  advocated  for  so  adapt- 
Proccaure.  ing  this  style  of  crown,  a  modification  of  the  one  de- 

vised by  Dr.  J.  G.  Hollingsworth  will  be  found  to  be 
the  most  generally  applicable  and  universally  practicable. 


208 


•  This  consists  in  preparing  the  root  as  previously  indicated  in  con- 
nection with  the  "band  and  dowel"  crown  and  the  Davis  crown  with  a 
band,  and  in  fitting  the  band  and  constructing  the  finished  cap  in  the 
same  manner  as  prescribed  for  the  former. 

The  crown  should  be  selected  in  accordance  with  the  details  indi- 
cated, and  this  may  be  observed  either  before  or  after  the  adjustment 
of  the  cap.  In  grinding  it  to  the  proper  adaptation,  however,  the  cap 
should  be  laid  aside,  and  the  adjustment  made  directly  to  the  root,  in 
which  procedure  the  original  form  of  the  base  of  the  crown  is  entirely 
changed,  and  it  is  only  necessary  to  observe  accuracy  along  the  labial 
edge.     (Fig.  171,  A.) 


When  a  moderately  accurate  adaptation  of  this  surface  has  been  se- 
cured, together  with  an  observation  of  the  remaining  requirements,  the 
cap  should  be  placed  in  position  on  the  root,  perforated  to  receive  the 
dowel,  and  the  final  adjustment  then  made  zvith  it  in  place. 

When  the  required  adaptation  has  been  thus  obtained,  the  base  of 
the  crown  should  be  further  ground  away  on  the  lingual  and  approximal 
edges  until  an  adequate  V-shaped  space  exists  between  this  portion  of  it 
and  the  cap.  The  space  should  be  large  enough  to  admit  of  being  subse- 
quently filled  with  solder,  by  which  means  the  crown  and  cap  are  per- 
manently attached,  but  should  be  no  larger  than  necessary  to  facilitate 


209 

this  procedure,  because  of  the  possible  weakening  of  the  attachment  of 
the  dowel  in  the  porcelain. 

The  perforation  of  the  cap  should  be  made  with  care  to  have  the 
dowel  at  closely  into  it,  as  a  preservation  of  the  accurate  relation  be- 
tween crown  and  cap,  and  the  facility  with  which  a  strong  union  be- 
tween them  may  be  effected,  will  depend  much  upon  such  a  relation.  In 
the  event  of  making  too  large  a  perforation,  an  additional  disk  of  thin 
gold  or  platinum  may  be  more  accurately  adjusted  to  the  dowel,  bur- 
nished to  place  on  the  cap,  and  separately  soldered  in  its  proper  position, 
thus  overcoming  any  possible  difficulties  in  this  connection. 

The  crown  should  now  be  backed  up  with  a  disk  of  platinum,  about 
36  gauge,  which  should  be  properly  perforated,  annealed,  and  closely 
burnished  to  place.  In  trimming  it  to  follow  the  outlines  of  the  base  of 
the  crown,  a  slight  Ungual  extension  (Fig.  171,  B)  should  be  allowed  to 
remain,  for  the  purpose  of  engaging  in  the  investment  material,  and  thus 
retaining  the  backing  in  close  proximity  with  the  porcelain  during  the 
process  of  soldering  If  this  precaution  is  not  observed,  the  backing 
will  invariably  be  drawn  away  from  the  base  of  the  crown,  as  a  result  of 
the  shrinkage  of  the  solder,  thus  diminishing  the  strength  of  the  union, 
and  affording  an  unhygienic  joint. 

A  backing  of  pure  gold  might  also  l)e  used  instead  of  platinum,  but 
the  extreme  thinness  necessary  to  admit  of  carrying  the  porcelain  well 
up  to  the  gingival  line  would  only  introduce  the  possibility  of  fusing  it 
during  the  process  of  filling  this  small  space  with  solder. 

When  the  backing  has  been  adjusted,  it  sliould  be  attached  in  posi- 
tion on  the  crown  with  melted  adhesive  wax  (Fig.  171,  C),  and  the  re- 
lation between  crown  and  cap  then  secured  on  the  root  (Fig.  171,  D), 
with  the  same  material.  To  accomplish  this  with  accuracy  and  facility, 
the  cap  should  be  placed  in  position  on  the  root,  kept  perfectly  dry,  a  little 
adhesive  wax  melted  on  the  backing  around  the  dowel,  and  the  crown 
then  quickly  carried  to  place  in  its  relation  to  the  cap. 

If  the  adhesive  properties  of  the  wax  are  not  destroyed  by  the  pres- 
ence of  moisture,  and  it  is  sufficiently  heated  to  admit  of  the  proper  ad- 
justment of  the  crown,  the  relation  will  be  securely  sustained,  and  crown 
and  cap  may  be  safely  detached  from  the  root  Avith  a  small  pointed  ex- 
cavator passed  around  the  edge  of  the  band. 

The  remaining  space  in  the  joint  should  then  be  completely  filled 
with  wax  (Fig.  171,  E),  and  the  crown  invested.  Previous  to  investing, 
the  lingual  extension  of  the  backing  should  be  bent  over  toward  the 
porcelain  tvithout  overlapping  upon  it,  until  it  may  be  so  engaged  in  the 
investment  material  as  to  be  held  in  place,  yet  offering  no  impediment 
to  the  soldering. 


210 

When  the  investment  has  crystaUized,  it  should  be  trimmed  down 
until  as  small  as  possible,  to  possess  sufficient  strength  to  hold  the  parts 
together.  The  wax  should  now  be  removed,  and  the  joint  between  cap 
and  backing  then  freely  exposed,  so  as  to  admit  of,  and  facilitate  being 
filled  flush  with  solder  (P"ig.  171,  F.)  The  case  should  now  be  fluxed, 
heated  thoroughly,  and  the  space  then  filled  with  18  karat  solder. 

In  soldering  such  crowns,  it  must  be  remembered  that  the  porcelain 
contains  a  large  mass  of  platinum,  hence  it  becomes  necessary  to  first 
heat  the  porcelain  well,  in  order  to  prevent  the  occurrence  of  a  fracture. 

In  filling  the  joint,  the  solder  should  be  cut  in  small  pieces,  ami 
each  one  of  these  consecutively  applied  and  fused,  to  assure  its  pene- 
tration to  the  full  depth ;  and  a  secure  attachment  to  the  dowel,  which,, 
being  covered  with  investment  material,  and  being  most  remote  from 
the  exposed  surfaces,  is  in  consequence  the  most  difficult  to  heat  thor- 
oughly. 

This  occasionally  accounts  for  a  failure  to  unite  the  crown  to  the  cap, 
arid  in  the  event  cf  such  an  accident  their  union  may  be  subsequently  ef- 
fected by  again  investing,  leaving  only  the  interior  of  the  cap  and  the 
dowel  exposed,  and  attaching  with  a  minimum  of  solder  at  the  point  of 
junction  between  the  two. 

The  contouring  of  the  solder  to  a  flush  smooth  surface  may  be  some- 
what facilitated  by  cutting  small  triangular  pieces  of  platinum  or  gold 
foil,  or  thin  plate,  and  adapting  them  to  the  approximal  sides  of  the  wax. 
in  the  joint,  before  investing,  thus  forming  a  matrix  for  the  solder. 

When  the  soldering  has  been  completed  and  the  cap  becomes  an  in- 
tegral part  of  the  crown,  it  should  be  finished  and  polished  as  usual  (Fig.. 
171,  G),  and  then  mounted. 

Uariation  of  lUctbods. 

Several  other  methods  of  securing  additional  stability  in  the  applica- 
tion of  such  crowns  are  employed,  and  at  least  two  of  them  miay  often  be 
used  to  advantage.  These  consist  in  excising  the  original  dozvel  and 
replacing  it  with  a  separate  one;  and  in  burnishing  or  szuaging  a  thin 
plate  to  the  basal  end  of  the  root  and  attaching  it  to  the  crown  and' 
dowel,  as  a  means  of  securing  a  more  perfect  adaptation  without  the  use 
of  a  band. 

Cases  not  infrequently  present  where  it  may  be 
Substituting  difficult  to   secure  a  proper  adjustment  of  a  Hxed- 

Separate  Dowels.       dowel  crown,  because  of  the  constricted  size,  or  un- 
favorable location  of  the  canal ;  or  the  position  or 
shape  of  the  root.    In  such  instances  the  accomplishment  of  good  results 
with  the  use  of  this  style  of  crown  may  occasionally  indicate,  or  eveUx 


211 

necessitate,  the  excision  of  the  original  dowel,  and  the  employment  of  a 
separate  one. 

When    this    procedure   seems    required,    the   cap 

Procedure.  should    be   constructed   as   usual,    and    an   ordinary 

platino-iridium  dowel  fitted  to  the  canal  and  soldered 

to  it,  allowing  but  a  slier t  projecting  end  to  extend  beyond  the  floor  and 

toward  the  porcelain,  so  as  to  ofifer  no,  or  a  minimum,  obstruction  to  the 

subsequent  adjustment  of  the  crown. 

A  suitable  crown  should  be  then  selected  and  its  dowel  cut  off  at  a 
point  about  1/16  of  an  inch  from  the  base,  when  it  may  be  ground  to  the 
proper  adaptation,  as  further  indicated  in  the  preceding  method.  It 
should  then  be  backed  up  in  a  similar  manner,  excepting  that  the  backing 
may  be  trimmed  to  follow  the  entire  outline  of  the  base  of  the  crown, 
and  separately  invested,  so  as  to  afiford  a  full  exposure  of  the  surface 
of  the  backing  (Fig.  172,  A).  When  properly  heated,  this  may  be  se- 
curely attached  to  the  short  projecting  end  of  the  dowel  witii  solder. 


The  proper  relation  of  the  crown  to  the  cap  (Fig.  172,  B)  may  now 
be  secured  and  sustained  with  adhesive  wax,  and  the  parts  removed,  in- 
vested and  soldered,  as  indicated.  The  finished  crown  is  illustrated  in 
Fig.  172,  C. 

As  the  degree  of  strength  obtained  in  the  union  of  the  crown  with 
the  cap  and  dowel  will  depend  much  upon  the  length  of  the  projecting 
end  of  each  dowel,  and  naturally  increase  in  proportion  thereto,  this  pro- 
cedure should  be  confined  to  extreme  cases,  or  to  those  wherein  the 
length  of  the  crown  may  admit  of  a  sufficient  exposure  of  the  ends  of 
the  dowels  to  insure  a  degree  of  integrity  in  the  finished  crown. 

A   method    of   securing   increased   accuracy   in 
Increased  JlCCUracv     the  adaptation  of  the  crown  to  the  root,  which  is 
Of  JIdaptation.         applicable  in  many  instances  where  it  is  not  desir- 
able to  employ  a  band,  was  perhaps  originally  sug- 
gested by  Dr.  Gordon  White,  of  Nashville,  Tenn. 


212 


This  consists  in  shaping  the  root,  adapting  the  crown,  and  chang- 
ing its  original  form,  as  previously  described. 

In  the  procedure  incident  to  the  employment  of 
Prcccdurc.  this  method,  a  disk  of  platinum  foil,  about  No.  40 

or  50,  is  annealed,  perforated  for  the  dowel,  and 
burnished  to  a  close  adaptation  to  the  base  of  the  crown,  after  the  latter 
has  been  properly  ground,  as  indicated  (Fig.  173,  A).  A  second  disk 
is  then  cut  somewhat  larger  than  necessary,  to  cover  the  end  of  the  root, 
and  closely  adapted  to  it,  thus  forming  a  V-shaped  space  between  the 
two  surfaces  of  metal  which  is  subsequently  filled  with  solder,  in  the 
manner  previously  outlined.     (Fig.  173,  B.) 

The  first  disk,  which  forms  a  backing  for  the  crown,  should  have  a 
slight  lingual  extension  for  the  purpose  of  sustaining  its  close  proxim- 
ity with  the  porcelain  while  soldering;  and  the  second  disk,  which  is 
adapted  to  the  base  of  the  root,  should  possess  a  slight  surplus  on  the 


lingual  surface,  Vk^hich  may  be  slit  and  burnished  up  over  this  portion  of 
the  root,  thus  resulting  in  the  additional  support  of  a  partial  band. 

In  securing  a  proper  and  close  adaptation  of  ea<^h  to  their  respec- 
tive positions,  the  first  disk  should  be  placed  in  position  on  the  crown, 
burnished,  and  trimmed,  and  then  attached  to  the  dowel  with  adhesive 
wax.  A  sufficient  quantity  of  the  latter  to  a  littlf  more  than  fill  the 
space  between  crown  and  root  should  then  be  placer^  over  this,  and  the 
second  disk  adjusted  to  position  on  the  wax  and  attached  by  touching 
it  with  a  hot  instrument.  The  wax  should  then  b^  chilled  with  cold 
water,  the  crown  and  disks  placed  in  position  on  the  root,  and  force 
enough  applied  with  a  piece  of  wood  and  small  mallet  to  carry  it  well 
to  place,  which  will  swage  the  second  disk  to  a  close  conformation  with 
the  base  of  the  root,  if  enough  wax  is  present. 

The  whole  should  then  be  removed  and  the  surplus  wax  trimmed 
down  flush  with  the  crown.  The  second  disk  may  now  be  trimmed  to 
closely  follow  the  outline  of  the  root,  excepting  upon  the  lingual,  which 


213 

portion  may  be  slit,  as  suggested,  and  burnished  up  over  this  surface  of 
the  root  upon  the  replacement  of  the  crown.     (F'ig.  I74-) 

When  this  has  been  accomplished,  it  should  be  removed,  and  in- 
vested, and  soldered,  with  an  observation  of  the  previously  mentioned 
requirements  and  precautions  in  this  connection,  and  the  finished  crown 
is  illustrated  in  Fig.  173,  C. 

In  roots  possessing  an  irregular  outline  or  concave  base,  this,  or  a 
similar,  procedure  may  be  found  advantageous ;  and  the  disk  which  is 
to  be  adapted  to  the  root  may  be  made  of  a  heavier  gauge  of  platinum 
when  indicated,  or  desirable,  in  the  manner  previously  recommended  in 
connection  with  the  "plate  and  dowel  crozvn." 

This    procedure    is    also    equally   applicable    to 

Porcelain  Ulork.       porcelain  work,  and  when  porcelain  is  preferable  to 

the  use  of  gold  solder,  for  uniting  the  plate  to  the 

crown,  the  details  differ  only  in   dispensing  with  the  first  disk,  as  this 


Fiq.174, 

Js  used  simply  as  a  backing  for  the  crown,   and  no  backing  becomes 
necessary  in  porcelain  work. 

The  adaptation  of  the  disk  to  the  base  of  the  root,  and  the  manner 
of  obtaining  and  sustaining  its  relation  to  both  the  crown  and  root,  may 
he  accomplished  as  indicated,  but  the  case  should  then  be  invested  and 
the  disk  permanently  attached  to  the  dowel  with  pure  gold,  or  twenty- 
five  per  cent  platinum  solder,  before  filling  the  intervening  space  with 
porcelain,  as  a  means  of  precluding  any  possible  change  of  relation 
which  may  accrue  as  a  result  of  the  shrinkage  of  the  porcelain  body  in 
fusing. 

Cbc  Brewster  Crown. 

Among  the  several  other  varieties  of  porcelain  crown  possessing 
fixed  dowels,  the  Brewster  crown,  designed  and  manufactured  by  IMr. 
Robert  Brewster,  of  Chicago,  111.,  is  more  or  less  extensively  em- 
ployed. 

It  is  made  of  porcelain  body,  quite  similar  to  Ash's  English  teeth, 
in  a  good  selection  of  moulds  and  colors,  with  a  slightly  concave  base. 


214 

and  a  round  dowel.  The  latter  is  made  of  a  composition  metal  similar 
to  the  alloy  of  German  silver,  and  is  attached  to  the  crown  with  a  low- 
fusing  body.  This  enables  it  to  possess  the  advantage  of  strength  and 
rigidity,  as  well  as  economy,  and  yet  the  attachment  between  crown  and 
dowel  seems  quite  secure  (Fig.  175,  A). 

The   application   of   this    crown   may  be   made 

Jlpplication.  whenever  the  employment  of  a  fixed  dowel  crown 

is  indicated,  or  desirable ;  either  with  or  without  a 
band  or  plate ;  and  the  detail  of  procedure,  in  each  instance,  is  identical 
with  that  indicated  for  the  Logan  crown,  excepting  that  the  composi- 
tion of  the  dowel  and  its  manner  of  attachment  in  the  porcelain  pre- 
clude its  use  in  connection  with  porcelain  work,  where  it  is  necessarily 
subjected  to  a  high  degree  of  heat  in  the  furnace ;  though  the  same 
readily  admits  of  the  use  of  20  karat  solder. 

The  favorable  shape  of  both  crown  and  dowel,  and  the  comparative 
■ease  with  which  it  may  be  procured  and  adjusted,  combined  with  its 


a 

ncf.l73, 

inexpensiveness,  make  it  very  useful  for  temporary  purposes;  but  when 
employed  as  a  permanent  crown  the  dowel  should  be  slightly  flattened 
on  at  least  one  side  (or  serrated),  in  order  to  facilitate  the  attachment 
of  the  cementing  medium,  and  thus  prevent  possible  rotation  or 
loosening. 

The  adaptation  of  the  base  of  the  crown  to  the  root  may  be  accom- 
plished with  greater  facility,  and  less  danger  of  grinding  the  dowel, 
by  the  use  of  curved  carborundum  wheels,  which  are  designed  and  rec- 
ommended by  Mr.  Brewster  for  this  purpose.     (Fig.  175,  B.) 

Cbe  **Teiiow$bip"  Crown, 

The  "Fellowship"  crown,  devised  and  manufactured  by  the  Dental 
Protective  Supply  Co.,  is  constructed  along  lines  similar  to  the  pre- 
ceding crown,  and  is  also  more  or  less  extensively  employed. 

Any  possible  rotation  of  the  crown  on  the  dowel,  or  in  its  attach- 
ment to  the  root,  is  prevented  by  the  shape  of  the  dowel,  and  the  manner 
in  which  it  is  attached  to  the  porcelain.  The  shape,  however,  is  similar 
to  that  of  the  dowel  of  the  Logan  crown,  and  in  consequence  possesses 


215 

the  same  objectionable  features,  it  is  made  of  a  German-silver  alloy, 
and  is  attached  in  the  crown  by  means  of  an  additional  piece  of  wire 
passing  laterally  through  perforations  in  the  base  of  the  crown  and  end 
of  the  dowel,  which  are  then  subsequently  filled  flush  with  low-fusing 
body.     (Fig.  176.) 

The  details  of  procedure  in  the  application  of 
HppliCfltiOn.  this  style  of  crown,  and  the  indications  for  its  em- 

ployment  are    practically    the    same   as    those   pre- 
viously described. 

Repairiiid. 

In  the  event  of  the  subsequent  occurrence  of  a  fracture  of  the  porce- 
lain in  any  of  the  various  forms  of  fixed-dowel  crowns,  the  method  of 
repair  is   often   difficult   and   sometimes  even   impossible  ;  and  the  best 


Fig.  176. 


results  are  usually  accomplished  by  removing  the  remaining  dowel  and 
adapting  a  new  crown. 

When  it  has  been  mounted  with  cement,  however,  and  particularly 
in  small  constricted  roots,  this  is  often  a  difficult  and  sometimes  dan- 
gerous procedure ;  but  may  be  accomplished  by  drilling  out  the  cement 
immediately  surrounding  the  dowel  with  a  very  small  round  bur  until  it 
may  be  gradually  loosened  and  removed,  in  which  extreme  care  must 
be  exercised  to  prevent  perforatmg  the  root  or  breaking  ofit  the  dowel  at 
a  point  which  will  likely  preclude  the  removal  of  its  apical  end. 

In  very  small  roots  or  where  either  of  the  latter  results  seem  at  all 
probable,  the  method  suggested  by  Dr.  Joseph  Head,  of  Philadelphia, 
may  be  employed  to  advantage.  This  consists  in  cutting  the  dowel  into 
two  lateral  halves  by  drilling  vertically  through  its  smallest  diameter 
with  a  small  round  bur,  and  when  so  divided,  the  space  thus  produced 
will  admit  of  loosening  each  half  until  their  separate  removal  may  be 
cfifected  without  danger  of  weakening  the  root.  A  pair  of  forceps 
designed  especially  for  this  purpose  by  H.  N.  Lancaster  may  also  be 
found  very  useful. 


2l6 

In  those  cases  where  the  dowel  remains  firm  in  its  attachment  to 
the  root,  and  the  length  and  strength  of  its  projecting  end  will  afford 
adequate  means  of  sustaining  a  new  porcelain  crown,  it  may  often  be  left 
in  place  and  a  Davis  crown  adapted  to  the  root  and  then  cemented  to  it; 
or,  a  crown  may  be  constructed  possessing  a  socket  in  its  base  which  will 
fat  and  engage  the  projecting  end  of  the  dowel  and  securely  sustain  it 
in  its  proper  relation,  when  mounted  with  cement.  As  this  latter  pro- 
cedure involves  the  construction  of  a  crown  which  may  often  be  found 
useful  and  practical  it  will  be  separately  considered  under  the  classifi- 
cation of  tube  croivns. 

This  style  of  crown  is  adaptable  to  that  class  of  cases  previously 
referred  to  wherein  the  original  has  been  broken  away  leaving  the  dowel 
still  firm  in  its  attachment  to  the  root ;  and  may  be  employed  as  a  means 
of  substituting  a  well  adapted  crown  when,  for  any  reason,  it  may  not 
be  deemed  advisable,  or  desirable,  to  remove  the  remaining  dowel. 

The  application  of  such  a  procedure  and  of  the  principles  involved 
was  probably  first  suggested  by  Dr.  Wm.  Mitchell,  of  London,  England, 
but  is  also  advocated  and  employed,  as  applied  particularly  to  porcelain 
work,  by  Dr.  Jas.  E.  Keefe,  of  Chicago,  111.,  and  Dr.  F.  J.  Capon,  of 
Toronto,  Canada. 

"While  the  application  of  such  crowns  is  neces- 

Hppiication.  sarily  confined  to  repair  work,  they  are  equally  ap- 

plicable to  cases  where  the  original  crown  pos- 
sessed a  band  and  cap,  which  may  or  may  not  remain  securely  in  place, 
as  well  as  to  those  where  no  band  was  used,  so  long  as  the  dowel  itself 
remains ;  but  the  strength  in  the  attachment  of  the  new  crown  will  of 
course  depend  upon  the  length  of  the  end  of  the  dowel  exposed  and 
projecting  beyond  the  surface  of  the  cap,  or  root,  which  may  be  tele- 
scoped by  the  tube. 

When  this  is  inadequate  the  opportunities  for  securing  sufficient 
integrity  may  be  increased  by  drilling  out  the  cement  around  the  dowel, 
and  thus  trephining  its  end,  with  a  small  round  bur,  until  a  greater 
length  is  exposed ;  but  where  a  cap  remains,  unless  the  dowel  projects 
sufficiently  far  beyond  it,  such  access  and  possibilities  may  indicate  its 
destruction  and  removal. 

When  the  dowel  has  been  thus  exposed  so  as  to  insure  sufficient 
stability  in  the  attachment  of  the  crown,  its  end  should  be  squared  up 
and  properly  shaped  to  admit  of,  and  facilitate,  the  adaptation  and 
easy  removal  of  a  telescoping  tube.      (Fig.    177,  A.) 


217 


This  tube  should  be  made  of  pure  gold  or,  plati- 

Prcccdure.  num,  about  36  gauge,  and  may  be  formed  on  a.piec<j, 

of  wire  previously  selected  for  the  purpose,  and  a. 

trifle  larger  in  diameter  than  the  dowel ;  or  foil  may  be  used  and  adapted 

directly  to  the   dowel,   if  subsequently   reinforced   with   solder ;  which 

should  be  also  observed  even  in  the  former. 

When  made  and  fitted,  the  joint  should  be  soldered,  and  the  tube 
then  adjusted  to  the  dowel.  A  disk  of  pure  gold  or  platinum,  as  the  re- 
quirements of  the  intended  construction  may  indicate,  about  36  gauge, ; 
should  now  be  perforated  to  fit  closely  over  the  tube,  burnished  to  a 
close  adaptation  to  the  root,  and  trimmed  to  follow  its  peripheral  outline. 
The  surplus  end  of  the  tube  should  now  be  cut  oflf  even  with  the  end  of 
the  dowel,  and  the  proper  relation  between  it  and  the  disk  securely  su.<;- 
tained  with  adhesive  wax,  when  they  may  be  detached  from  the  root  and 
invested  and  soldered,  at  which  time  the  open  end  of  the  tube  presenting 


Fjq.177. 


toward  the  incisal  edge  should  be  closed.  This  affords  an  accurately 
adapted  base  for  the  subsequent  construction  of  a  crown  in  the  ordinary 
manner,  using  a  facing  in  combination  with  either  gold  or  porcelain, 
which  may  then  be  finished  and  mounted  with  cement. 

The  completed  crown  for  that  class  of  cases  where  the  end  of  the 
dowel  projects  far  enough  beyond  the  base  of  the  root  to  afford  adequate 
stability  in  the  attachment  is  illustrated  in  Fig.  177,  B;  while  the  con- 
struction for  those  cases  wherein  the  end  of  the  dowel  is  trephined  and 
the  tube  thus  extended  into  the  root,  as  a  means  of  securing  greater 
integrity,  is  illustrated  in  Fig.  177,  C,  and  the  relation  pf  the,  finished 
crown  to  the  root  and  dowel  in  the  former  class  is  illustrated  in  Fig. 
177,  'D.  ,.  .. 

Ccmporary  €rown$.  vi    i 

The  employment  of  temporary  crowns  become  necessary  in  emer- 
gency cases  where  immediate  substitution  of  the  lost  natural,  c^r,  b,i^o^e^ 
artificial,  crown  is  required;  and  is  indicated  in  the  construction  oi  per" 


2l8 

manent  crowns  for  the  anterior  teeth,  for  the  purpose  of  relieving  the 
patient  of  temporary  disfigurement  and  embarassment  during  the  pro- 
cedure. Their  use  also  materially  facilitates  the  subsequent  adjustment 
and  mounting  of  the  permanent  crown  by  keeping  the  gum  packed 
away  and  preserving  a  free  exposure  of  the  end  of  the  root,  during  the 
interim. 


Fic].l78, 

In  view  of  the  possible  advantages  thus  derived 
Tndications.  from  their  use  in  the  application  of  dowel  crowns, 

'     '  and    particularly    in    the    mouths    of    women,    they 

should  be  invariably  employed  whenever  the  time  required  to  complete 
the  construction  of  a  permanent  crown  precludes  finishing  and  mount- 
ing the  latter  on  the  same  day  on  which  the  root  is  prepared. 

While  almost  any  of  the  fixed-dowel  crowns,  and  especially  the  less 
expensive  ones,  will  often  answer  this  purpose,  and  even  the  old-style 
English  tube-teeth  may  be  employed,  the  most  simple,  expeditious  and 
inexpensive  method  consists  in  using  an  ordinary  long-pin  facing,  and 
constructing  the  crown  for  the  individual  case. 


FicjJ79. 

To   facilitate  the    application,   at  least   a  small 
PfOCedure.  selection  of  facings  for  the  six  anterior  teeth  should 

be  kept  on  hand.  One  suitable  to  the  requirements 
of  the  case  in  size,  shape  and  color,  should  then  be  selected  and  ground 
to  a  fairly  good  adaptation,  and  a  dowel  then  made  of  German-silver 
wire.  Such  wire  is  c-onvenient  for  many  purposes  and  may  be  easily 
procured  in  six-inch  lengths  of  various  sizes  from  jewelers'  supply 
houses.     Fig.  178. 


219 

A  proper  length  and  size  of  dowel  should  he  cut,  one  end  slightly 
iapered  with  a  file,  and  the  other  flattened  with  a  small  hammer  on  the 
anvil,  Fig.  179,  or  by  pressing  between  rollers,  Fig.  180,  both  of  which 
are  useful  appurtenances  for  the  well  equipped  laboratory,  until  it 
is  broad  enough  to  fit  in  snugly  between  the  pins.  This  is  done  for  the 
purpose  of  facilitating  the  attachment  of  the  facing,  and  preventing  any 
obstruction  to  the  occlusion,  but  should  not  be  done  with  a  file,  because 
of  thus  unnecessarily  diminishing  the  strength  of  the  dowel  at  this 
point. 

The  most  convenient  method  of  attaching  the  facing  and  dowel  has 
been  suggested  by  Dr.  W.   H.  Taggart,  of  Chicago,  111.     In  this  pro- 


r-icj.l80. 

cedure  the  flattened  end  of  the  dowel  is  made  somewhat  broader  than 
the  space  between  the  pins  of  the  facing,  and  then  notched  with  the 
edge  of  a  file  until  it  may  be  slipped  into  place,  with  the  pins  fitting 
closely  into  the  notches.  The  permanent  relation  between  the  two  may 
then  be  securely  sustained  by  bending  the  pins  over  upon  the  dowel. 

The  dowel  should  now  be  bent,  if  necessary,  until  the  crown  may 
be  properly  adjusted  to  position  on  the  root,  when  it  should  be  mounted 
with  temporary  stopping  or  gutta  percha,  with  which  the  desired  con- 
touring of  the  lingual  surface  can  also  be  made.  The  consecutive  steps 
of  this  entire  procedure  are  illustrated  in  Fig.  181. 


220 

Temporary  stopping  may  be  used  with  greater  facility  and  pos- 
sesses sufficient  integrity  to  serve  the  purpose  for  a  few  days,  but  when 
the  crown  is  to  be  worn  for  a  longer,  or  more  indefinite  period,  gutta 
percha  should  be  used. 

Although  the  detail  incident  to  the  construction  of  such  crowns 
consumes  but  five  or  ten  minutes'  time,  an  assortment  of  these  dowels 
may  be  made  at  convenient  opportunities,  and  kept  for  subsequent  use,, 
which  will  further  expedite  the  work. 

The  relation  between  facing  and  dowel  may  be  also  sustained  by  the 
use  of  either  hard  or  soft  solder,  if  desirable,  but  a  more  secure  attach- 
ment than  is  afforded  by  the  above  method  is  seldom,  if  ever,  required. 

In  the  use  of  gold  or  silver  solder  for  such  purposes  the  facing  and 
dowel  should  be  attached  by  bending  the  pins,  and  the  whole  then  in- 
vested and  soldered  in  the  usual  manner.  In  using  soft  solder,  however, 
no  investment  is  necessary  if  the  facing  and  dowel  are  placed  upon  a. 
slightly  heated  charcoal  or  asbestos  block  or  in  a  bed  of  asbestos  fibre;. 


I   1  1 


the  proper  flux  then  applied,  and  evaporated  with  heat,  and  the  solder  then 
fused  by  slowly  directing  the  flame  of  a  Bunsen  burner  or  alcohol  lamp 
upon  the  facing. 

A  more  artistic  and  finished  contour  of  the 
U$C  Of  JImalsam.  Ungual  surface,  as  well  as  a  more  permanent  adapta- 
tion of  such  crowns  may  be  obtained  by  placing  the 
facing  and  dowel  (after  their  attachment)  upon  the  root,  and  packing 
plastic  amalgam  over  its  end,  and  around  the  dowel,  to  the  desired  contour. 
After  this  has  crystallized,  it  may  be  finished  and  polished,  and  then 
mounted.  This  procedure  consumes  more  time,  and  entails  more  work 
than  is  usually  indicated  or  warrantable  for  temporary  purposes. 

More  artistic  and  permanent  results  may  also 
Use  Of  Uulcanite.  be  obtained  by  adapting  the  base  and- forming  the 
lingual  contour  with  wax,  and  subsequently  flask- 
ing  the  crown  and  replacing  the  wax  with  vulcanite.  In  the  process, 
however,  it  becomes  necessary  to  "tin"  the  German-silver  dowel,  so  that, 
the  vulcanite  may  become  attached  to  it,  and  the  entire  procedure  re- 
quires more  time  than  that  incident  to  the  construction  of  a  crown  in  a. 
more  practical  and  artistic  manner. 


Jlpplicmion  ana  Construction  of  Porcelain  Crowns. 


CHAPTER   XII. 


Contraindications.     Indications.     Advantages :       Esthetic ;     Anterior     Crowns,     Bi- 
cuspid Crowns,  Molar  Crowns.    Hygienic.      Mechanical ;    Attachment    of    Facing, 
Attachment  of  Molar  and  Bicuspid  Crowns    to   Root.      Application :      Require- 
ments ;   Strength  of  Metal  Construction,  Soldering,  Oxyhydrogen  Flame,  Root 
Preparation.     With  Band  and  Dowel :   Bands,   Floor,   Dowels,  Accurate   Fit- 
ting Dowels,  Impression  and  "Bite,"  Facing.  Investment,  Soldering  Facing, 
Anterior  Crowns,  Bicuspid  Crowns,  Molar  Crowns ;  With  Facing,  With- 
out Facing.     Variations  in  Construction :    Re-enforced  Caps ;  Proced- 
lu-e.     Without    Band;    Procedure,  Plate  and  Dowel.  Partial  Bands  ; 
Procedure.     Jacket  Crowns;  Indications     for     Porcelain    Jackets, 
Procedure.     Variation  of  Method.      Use     of     the     Davis     and 
Logan   Crowns ;   Advantages,  Disadvantages.     Application  of 
the      Davis      Crown,      With        Band,        Without       Band. 
Application      of     the      Logan      Crown ;      Procedure. 


After  having  passed  through  the  various  experimental  stages  in- 
cident to  the  development  of  its  possibilities,  the  application  of  porcelain 
v^rork,  or  the  ceramic  art  has  opened  one  of  the  most  artistic  and  prac- 
tical fields  of  dentistry,  and  is  without  doubt  destined  to  become  a  perma- 
nent part  of  modern  practice. 

While  the  primitive  efforts  in  this  line  were  fraught  with  many  dis- 
couraging phases,  and  replete  with  failures,  and  much  of  the  resultant 
development  must  be  attributed  to  the  ever-increasing  and  constantly  im- 
proving facilities ;  yet,  throughout  the  entire  era  of  its  employment,  from 
the  time  when  the  material  was  supplied  in  only  one  or  two  grades  and 
colors;  when  the  coke  furnaces  afforded  the  only  adequate  means  for 
obtaining  sufficient  heat,  and  when  the  "baking"  of  a  case  required  con- 
siderable effort  and  consumed  much  time,  until  the  present,  when  it  can 


222 


be  procured  in  several  grades  and  in  varying  colors ;  when  the  same 
procedure  may  be  accomplished  in  the  operating  room  in  the  presence  of 
the  patient,  instead  of  the  laboratory,  at  night ;  and  at  the  expense  of  but 
little  time  or  effort,  the  possibilities  of  such  work  from  an  artistic  point 
of  view  have  always  been  fully  appreciated. 

Since  porcelain  is  a  mineral  substance,  however,  and  in  consequence 
possesses  the  characteristic  of  friability,  the  possibilities  from  the  view- 
point of  strength — which  as  a  requirement  is  of  equal  importance  with 
the  esthetic — have  been  observed  and  recognized  only  in  its  more  modern 
application ;  and  have  been  attained  mainly  as  the  result  of  continued 
experimentation  on  the  part  of  those  who  were  sufficiently  enthusiastic 
and  progressive  to  ascertain  the  causes  of  failures,  and  endeavor  to  over- 
come them  by  the  elimination   of  weak  points. 

As  a  result,  the  use  of  porcelain  in  its  present  form,  and  with  the 
facilities  available,  make  it  possible  for  the  skilful  and  experienced  ope- 
rator to  achieve  results  which  combine  both  of  these  requirements  to  a: 
high  degree.  This  is  especially  true  of  its  application  to  crown  and 
bridgework,  in  which  its  conservative  employment  may  be  productive  of 
a  class  of  work  which  more  closely  approaches  the  ideal  than  any  other,, 
by  conserving  the  very  highest  possible  esthetic  and  mechanical  require- 
ments. 

In  view  of  the  friable  nature  of  porcelain,  however,  the  desired  and 
necessary  degree  of  strength  is  not  to  be  obtained  from  thin  layers,  or 
veneers,  but  is  dependent  upon  the  presence  of  a  sufficient  thickness  tO' 
insure  the  requisite  resistance  to  stress.  For  this  reason  the  possible 
strength  of  such  work  will  naturally  increase  in  proportion  to  the  quantity 
which  may  be  used  in  the  individual  case,  or  in  proportion  zvith  the  bulk; 
and  for  the  latter  reason,  porcelain  work  in  any  of  its  phases  is  not  uni- 
versally applicable,  but,  on  the  contrary,  has  its  definite  prescribed  limita- 
tions. 

Hence  the  entire  practicability  of  this  class  of  work  will  depend  upon,, 
first,  conservative  or  judicious  application,  and  second,  a  skilful  execution 
of  all  of  the  details  incident  to  the  construction. 

The  absolute  necessity  for  scrupulous  attention  to  detail,  and  for  the 
utmost  of  painstaking  care  in  its  execution  accounts  to  a  large  extent  for 
the  occurrence  of  failures,  and  elevates  this  class  of  work  to  a  plane  some- 
what beyond  the  ordinary.  Indeed,  the  successful  manipulation  of  porce- 
lain promotes  and  demands  the  acquirement  of  a  degree  of  skill,  and  the 
cultivation  of  an  artistic  temperament,  which  is  far  beyond  the  province 
of  those  whose  efforts  are  more  or  less  encompassed  within  the  range  of 
indifference. 

While  failures  will  occur  in  any  line  of  work,  a  very  large  proportion 


223 

of  them  in  this  particular  class  can  invariably  be  attributed  to  an  inade- 
quate conception  of  the  requirements,  or  injudicious  application;  or  to 
unskilful  or  faulty  construction  and  manipulation;  either,  or  all,  of  which 
should  reflect  upon  the  inexperience  or  indifference  of  the  operator  rather 
than  to  cause  or  result  in  a  premature  condemnation  of  principles,  methods 
and  materials  involved. 

Contraindications. 

For  these  apparent  reasons  the  application  of  porcelain.^©  the  con- 
struction of  individual  croivns,  to  which  consideration  this  chapter  will 
be  exclusively  devoted,  is  contraindicated  in  all  cases  where  the  maximum 
length  of  the  crown,  or  the  close  occlusion  of  the  opposing  teeth,  precludes 
the  presence  of  porcelain  in  snificicnt  thickness,  or  hulk,  to  insure  an  ade- 
quate degree  of  strength;  and  where  nothing  but  an  indestructible  sub-_ 
stance,  like  metal,  could  be  relied  upon  to  withstand  the  stress  of  masti- 
cation. 

Indications. 

As  such  cases  present  the  exceptional,  rather  than  the  usual  condi- 
tions, however,  and  hence  constitute  a  small  percentage  of  those  requiring 
a  restoration  of  the  natural  crown,  the  application  of  porcelain  crowns, 
properly  constructed,  is  especially  indicated  on  the  ten  anterior  teeth,  and 
not  infrequently  ui^on  the  molars,  in  all  cases  which  present  ^n'&vm&i  or 
average  favorable  occlusion.  ■-:■■■.    ■  :■.■  ■■■■'x 

The  special  advantages  to  be  obtained  from  the  application  of  porce- 
lain ci;owns  lie  in  the  artistic  manner  and  facility  with  which  the  natural 
conditions  and  varying  characteristics  may  be  closely  simulated ;  the  hygi- 
enic qualities  of  the  material,  and  the  possibilities  for  comparative  and 
relative  strength.  These  may  be  classified  as  esthetic,  hygienic  and  me- 
chanical and  each  will  be  separately  considered. 

While    the    possibilities    for    avoiding  any  dis- 
€$tbctlc,  play    of    gold    are    always    very    advantageous    this 

esthetic  feature  is  further  supplemented  by  the  ab- 
sence of  a  metal  backing,  the  use  of  which  particularly  on  the  anterior 
teeth  is  always  more  or  less  objectionable. 

In  the   construction   of  crowns  for  the  six  an- 

Jlnterior  €rown$.      terior  teeth   the  reflection  of  the  rays  of  light  and 

its  variations  bear  materially  upon  the  color  problem, 

and  more  artistic  results  are  always  to  be  obtained  from  the  absence  of 

a  metal  backing  for  the  reason  that  its  presence  destroys  the  transhicency 

of  the  porcelain  facino;;  changes  its  color,  and  often  occasions  the  appear- 


^24 

arice  'Of  a  dark  blue  line  along  the  point  between  facing-  and  backing.  This 
ktter  unsightly  and  unhygienic  condition  is  due  to  the  penetration  and 
decomposition  of  secretions,  and  is  of  course  decidedly  objectionable. 
While  the  translucency  of  the  facing  is  slightly  diminished  even  in  a 
porcelain  crown,  it  is  by  no  means  destroyed^  and  the  other  objectionable 
features  are  entirely  eliminated,  all  of  which  are,  particularly  in  this 
region,  especially  important  considerations. 

In   the   restoration   of  the   crowns   of  bicuspids 
"    BlCtU^id  Crowns.       the  employment  of  porcelain  is  especially  indicated 
■r  '    ,'  because    of    the    difficulty    of    obtaining    the    same 

esthetic  effect,  combined  with  the  required  degree  of  strength,  in  any 
'Ottie'r  style  of  construction.  Indeed  the  ease  and  facility  with  which 
both  of  these  features  may  be  obtained,  as  compared  with  any  other  style 
of  crown,  causes  its  application  to  be  pre-eminently  indicated  on  these 
ieeth. 

^x,  Although  color    and    translucency    are    not    sa 

nidldf  Crowns.  essentially  important  a  consideration  in  crowning  the 
molars,  and  granting  the  previously  mentioned  ad- 
vantages of  the  gold  shell  or  telescope  crown  for  these  teeth,  there  are 
nevertheless  frequent  indications  for  the  application  of  porcelain  crowns. 
Often  on  the  first,  and  occasionally  on  the  second  molars,  and  particularly 
in  the  mouths  of  women,  gold  crowns  are  more  or  less  conspicuous,  and 
the  use  of  porcelain  may  serve  a  highly  esthetic  purpose  in  these  cases. 

The  hygienic  properties    of    a    smooth,  highly 
I)y0icniC.  vitrified  surface,  like  that  which  presents  in  porce- 

-  ,  lain,  constitute  an  important  advantage  of  inestim- 

able Valiie  in  the  mouth.  Such  a  surface  is  more  easily  kept  clean  than 
that  of  gold  because  it  is  immune  to  the  chemical  action  of  the  secretions, 
and  food  products  will  not  cling  to,  become  deposited  upon,  or  be  ab- 
sorbed by  it.  For  this  reason,  and  possibly  also  because  of  its  property  of 
slow  conductivity,  it  is  least  irritating  to,  and  most  compatible  with,  the 
tissues  of  the  mouth. 

Those  advantages  which    have    been    classified 
m^Cltanical.  as  mechanical  will  be  considered  from  the  view-point 

of  the  relative  degree  of  possible  strength  which 
may  be  obtained  both  in  the  construction  of  the  crown,  and  in  its  attach- 
ment to  the  root. 

As  the  attachment  of  the  facing  is  usually  the 

JIttacbment  of  facing,   weakest  point  in  the  construction  of  dowel  crowns, 

in  this  connection  the  relative  strength  to  be  obtained 

from  this  style  of  construction  as  compared  with  a  metal  backed  crown 

is 'a  matter  of  much  concern  and  of  appreciable  importance. 


22,5 

The  probability  of  the  subsequent  occurrence  of  fractured  facings 
in  porcelain  crown  work  is  reduced  to  a  minimum  for  the  reason  that, 
in  a  metal  backed  crown  the  facing  is  attached  to  the  backing  simply  and 
only  by  means  of  the  attachment  pins,  while,  in  a  porcelain  crown,  this 
same  attachment  is  also  secured  and  then  further  supplemented  by  the 
fusion  of  the  porcelain  over  the  entire  lingual  surface  of  the  facing. 

The  additional  strength  thus  obtained  by  this  combined  means  of  at- 
tachment makes  it  practically  impossible  for  the  facing  to  be  broken  away 
from  a  well  constructed  crown.  When  such  breakage  or  accident  does 
occur,  the  entire  mass  of  porcelain,  including  facing,  will  usually  separate 
from  the  cap,  which  rarely  happens,  and  which  can  be  quite  as  often 
attributed  to,  and  invariably  indicates,  faulty  construction  of  the  crown 
with  regard  to  the  means  observed  for  the  support  and  retention  of  the 
porcelain. 

In  the  attachment  of  molar  and  bicuspid  crowns 
nttachmcnt  of  Ittolar  to  the  root  a  possible  mechanical  advantage  is  also 
and  Bicuspid  €rown$.  possessed,  even  over  gold  crowns,  because  of  the 
greater  facility  with  which  a  short  projecting  end 
of  the  root  may  be  properly  prepared,  and  a  narrow  band  accurately  fitted, 
as  compared  with  the  requirements  incident  to  shaping  a  longer  project- 
ing end  of  the  root  and  adapting  a  wider  band. 

While  the  latter  procedure  may  be  somewhat  more  difficult,  any  pos- 
sible-advantage reverts,  however,  to  the  degree  of  skill  with  which  the 
detail  is  executed,  and  unless  the  esthetic  requirements  indicate  the  appli- 
cation of  a  porcelain  crown,  or  the  root  is  primarily  destroyed  to  a  close 
proximity  with  the  gum  line,  the  preference  should  usually  be  given  to 
the  gold  crown  because  of  the  conservation  of  tooth  structure,  and  of  the 
increased  strength  in  the  attachment  between  crown  and  root  which  may 
possibly  be  obtained  in  the  use  of  a  wider  telescoping  band. 

In  the  application  of  this  class  of  crown  construction  the  highest  pos- 
sible advantages  can  be  derived  only  from  a  careful  observation  of  the 
requirements,  combined  with  a  skilful  execution  of  the  details  in  the 
preparation  of  the  root ;  the  construction  and  adaptation  of  the  cap,  and 
attachment  of  the  facing;  and  the  manipulation  of  the  "body"  itself. 

When  the  conditions  of  occlusion  are,  or  may  be  made,  favorable, 
and  when  these  details  of  construction  have  been  executed  with  skill,  a 
porcelain  crown  possesses  adequate  strength  to  meet  the  requirements 
in  all  average  and  typical  cases ;  and  the  possible  integrity  in  such  work 
often  exceeds  that  of  any  other  style  of  construction. 


226 

To  obtain  such  results  with  a  maximum  degree 

KCQUircincnfS.  of  strength,  however,  three  essential  requirements 
must  be  observed :  First,  the  cap,  or  base,  of  the 
crown  must  be  inherently  strong  enough  to  retain  its  shape,  and  afford 
ample  means  of  attachment  and  support  to  the  porcelain.  Second,  the 
facing  must  be  properly  adapted,  and  securely  attached  to  the  cap;  and 
third,'  the  selection  and  manipulation  of  the  "body"  must  be  made  with  a 
view  to  securing  the  best  possible  results. 

In   order  that  the  requisite  strength  may  exist 
Strenstl)  of  metal      in  the  metal  parts  they  must  be  made  of  a  material 

Construction.  which  will  withstand  the  degree  of  heat  required  tO' 

fuse  the  porcelain ;  and  a  gauge  sufficiently  thick  tO' 
retain  its  given  shape  must  be  used.  Because  of  the  practical  infusibility 
of  platinum,  of  its  malleability,  slight  susceptibility  to  oxidation,  and  tO' 
the  chemical  action  of  the  secretions,  it  is  used  almost  exclusively  for  alt 
of  the  parts  for  this  work,  excepting  the  dowel.  For  this  purpose  the 
alloy  of  platinum  and  iridium  is  used  because  of  the  softness  of  platinum 
alone,  and  of  the  additional  stiffness  imparted  by  the  incorporation  of 
various  proportions  of  the  latter  metal. 

In   soldering  the   various   parts   perfect  contact 
Soldering.  between  all  joints  to  be  united  should  exist,  and  their 

union  must  be  effected  with  a  grade  of  solder  which 
will  not  be  disturbed  or  re-fused  in  the  subsequent  "baking"  of  the  crown. 
For  this  reason  2y/r  platinum  solder  should  be  used  throughout  the  entire 
assemblage  of  metal  parts  if  the  greatest  degi'ee  of  strength  is  to  be  ob- 
tained, and  its  use  is  absolutely  nccessary"wheTk\^QV:€pnta.ct  does  not  exist. 

In  the  construction  of  single  crowns,  however,  (all  of  the  soldering 
may  be  done  successfully  with  the  tise  of  pure  gold  as  a  solder,  provided 
that  absolute  contact  of  the  parts  has  been  secured,  and  that  the  gold  ,is 
then  thoroughly  fused  until  all  surplus  disappears  by  becoming  absorbed 
by,  and  alloyed  zvith,  the  platinum. 

This  may  be  easily  accomplished  by  the  continued  application  of  a 
small  pointed  flame  from  the  ordinary  combination  mouth  blow-pipe,  and 
will  be  indicated  by  the  disappearance  of  the  surplus,  and  the  blending 
of  its  color  into  that  of  the  platinum.  To  secure  this  result  with  facility, 
however,  it  is  highly  important  that  only  enough  gold  should  be  used  to 
make  the  joint,  and  such  a  union  will  possess  strength,  and  successfully 
withstand  the  degree  of  heat  necessary  to  fuse  the  porcelain. 

Should  absolute  contact  not  exist  at  any  point  in  the  joint  the  disap- 
pearance of  the  pure  gold  solder,  which  may  be  due  either  to  absorption 
or  to  volatilization,  will  result  in  a  subsequent  opening  and  weakening  of 
the  joint,  either  from  the  heat  of  the  blow-pipe  or  furnace. 


22/ 

Tn  the  use  of  platinum  sulders.   whether  or  not 

Oxybydroaen  TIame.    an  investment  is  employed,    the    use    of    the    oxy- 

hydrogen  flame  is  expedient,  and  often  abs(jlutel\ 

essential,  and   while  the   same   might  also  be  used  with,  jnire  gold,  it  is 

entirely  unnecessary. 

As  those  requirements  incident  to  the  attachment  of  the  facing,  and 
the  manipulation  of  the  body,  constitute  important  procedures  in  the  con- 
struction of  the  crown,  they  will  be  c(jnsidered  in  regular  order. 

The  requirements  of  root  preparation  are  sim- 

Koot  Preparation.       ilar  to  those  previously  indicated  in  the  application 

of  any  of  the  various  styles  of  dowel  crowns,  with 

the  exception  that,  for  porcelain  work,  the  root  should  be  cut  down  until 

as  short  as  consistent  in  order  to  secure  as  much  space,  and  make  as  much 

accommodation  for  the  porcelain  as  possible. 

While  an  unnecessary  wast«  or  sacrifice  of  tooth  structure  is  to  be 
condemned  as  a  general  practice,  for  the  above  reason  the  root  should 
be  cut  shorter  for  porcelain  crowns  than  for  any  other  style  of  construc- 
tion, but,  //■  (7  band  is  to  be  employed  a  projectiui^  surplus  end  should  al- 
ways be  allowed  to  remain  until  the  peripheral  trimming  has  been  accom- 
plished, the  measurement  taken,  and  the  band  fitted.  This  is  necessary 
for  the  reasons  previously  mentioned  in  connection  with  the  "band  and 
dowel"  crown,  and  the  same  shape  is  indicated  for  the  basal  end  of  the 
root  as  formerly  recommended  and  illustrated  for  anterior  roots  in  Fig. 
50,  and  for  bicuspid  and  molar  roots  in  Fig.  53. 

mitl)  Band  and  Dowel. 

As  the  employment  of  a  band  is  generally  conceded  to  be  productive 
of  the  most  universally  successful  results,  this  style  of  construction  will 
be  ^iven  precedence  in  this  consideration,  and  be  followed  by  the  varia- 
tions, the  indications  for  the  application  of  each  of  which  having  been 
previously  mentioned. 

The    band    should    be    made    of    platinum    not 
Bands.  thicker  than  28  nor  thinner  than  29  gauge,  and  the 

edges  should  be  slightly  overlapped  before  solder- 
ing. This  method  should  be  observed  as  a  means  of  securing  additional 
strength,  and  of  precluding  the  subsequent  opening  of  the  joint  from 
the  expansion  of  the  metal  which  is  induced  by  the  degree  of  heat  neces- 
sary to  fuse  the  porcelain.  The  exact  length  of  the  measurement  of  the 
root,  taken  in  the  ordinary  manner,  and  cut  and  straightened  as  indi- 
cated, should  be  designated  by  cutting  a  small  nick  in  the  edge  of  a  piece 
of  platinum  plate  from  which  the  band  should  then  be  cut  about  Vg  of  an 
inch  wide,  and  with  an  allowance  of  about  i/i6of  an  inch  surplus.    (Fig. 


22^ 


182A.)  Each  end  should  then  be  slightly  beveled  on  one  side  with  a 
iile,  and  the  band  then  annealed  and  made  in  circular  form,  with  the  sur- 
plus end,  designated  by  the  nick,  overlapping  the  outside  of  the  other 
end  until  the  nick  approximates  evenly  with  this  edge.     (Fig.  182  B.) 

The  surplus  overlapping  end  must  be  on  the  outside  to  prevent' 
diminishing  the  size  of  the  band,  and  the  relation  may  then  be  sustained 
by  pinching  the  ends  closely  together  with  flat-nose  pliers,  which  pro-' 
duces  a  sharp  angle  on  each  side  of  the  joint  and  affords  a  flat  surface' 
contact.  (Fig.  182  C.)  This  will  usually  overcome  a  change  in  the  re- 
lation as  the  result  of  expansion  when  heated,  though  ■  a  wire  may  be 
twisted  around  the  band  for  this  purpose  if  necessary. 

The  joint  should  then  be  soldered  with  a  mininium  quantity  of  25 
per  cent  platinum  solder,  or  with  pure  gold,  to  prevent  unnecessary  stiff- 
ness, in  the  manner  indicated. 


The  band  should  now  be  trimmed  to  follow  the  cervical  curvature 
of  the  gum,  the  edge  nicely  rounded,  and  then  fitted  to  the  root,  and 
afterward  cut  away  until  as  narrozv  as  possible,  in  accordance  with  the 
detail  previously  described. 

The  floor  should  be  of  about  32  gauge  platinum 
floor.  cut  somewhat  larger  than  the  diameter  of  the  band. 

The  band  should  be  placed  in  position  on  it,  and 
iirst  simply  tacked  to  place  with  a  small  quantity  of  solder.  This  primary 
attachment  secures  the  relation  and  anneals  the  floor  metal  so  that  it  may 
then  be  easily  burnished  into  close  and  direct  contact  with  the  edge  of 
the  band,  without  danger  of  changing  the  shape  of  the  latter. 

The  soldering  may  now  be  completed  in  which,  if  pure  gold  is  used, 
it  must  be  carefully  noted  that  perfect  contact  exists  around  the  entire 
joint,  alter  which  the  surplus  may  be  trimmed  away  and  finished  down 
with  file  and  disks  until  flush  with  the  edge  of  the  band. 


229 

The  dowel  should    be    made    of    round    iridio- 
DOWelS.  platinum   zvi're  of  a  size  proportionate  with  the  size 

(;f  the  root  and  requirements  of  the  crown,  and  fitted 
to  the  canal  in  the  manner  previously  outHned. 

The  cap  should  now  be  adjusted  to  place  on  the  root,  the  floor 
shghtly  perforated  for  the  dowel  at  the  proper  point,  and  this  perfora- 
tion then  enlarged  with  the  dowel  by  forcing  it  to  place.  This  insures 
a  perfect  contact  between  them  which  is  essential  to  the  strength  of  their 
union,  and  to  the  facility  with  which  it  may  be  accomplished. 

The  relation  should  now  be  temporarily  sustained  with  gutta-percha 
or  adhesive  wax,  until  they  may  be  removed,  invested,  and  soldered  as 
indicated.  While  any  means  of  investment  is  often  unnecessary  because 
of  the  close  relation  thus  existing,  the  simple  means  previously  advo- 
cated for  this  insures  their  proper  relation. 

Where   it  may   be   desirable  to  have  the  dowel 

JlCCUrate  Tiffing       fit  closely  to  the  walls  of  the  canal  througfhout  its 

Dowels.  entire   length,   the  method   suggested  by  Dr.  A.  O. 

Hunt,  and  others  may  be  used  to  advantage.     This 

consists  in   rolling  platinum  foil    i-iooo  into  a  cone,  passing  this  cone 

into  the  canal  and  expanding  it  first  with  a  tapering  pointed  instrument, 

and  then  by  packing  cotton  into  it,  until  it  conforms  to  the  shape  of  the 

canal.     It  may  now  be  removed  and  filled  with  platinum  solder,  and  then 

adjusted  to  its  proper  relation  with  the  cap,  as  indicated. 

The  same  procedure  is  also  applicable  to  any  kind  of  crown  con- 
struction, and  for  gold  work  the  cone  may  be  filled  with  scrap  gold  or 
solder. 

While  iridio-platinum  wire  of  a  suitable  size  will  usually  meet  all 
of  the  requirements  of  a  dowel,  one  constructed  in  this  manner  possesses 
■the  advantage  of  being  largest  at  the  junction  betzueen  crozvn  and  roof 
which  is  of  course  the  weakest  point  in  the  attachment  of  any  kind  of  a 
dowel  crown ;,  and  the  use  of  such  a  dowel  may  be  especially  indicated 
m  those  cases  where  the  canal  has  become  abnormally  enlarged  from  decay. 

When  the  cap  has  been  completed  and  finished, 

Tmpm$!on  and  adjusted  to  its  proper  position  on  the  root,  the 

and  "Blt«."  usual   impression   should   then   be   taken    in   plaster, 

and   this  preceded,  whenever  necessary,  by  a  "bite" 

in  wax. 

After  securing  the  impression,  it  should  be  observed  that  the  cap 
rests  firmly  in  place  in  it,  and,  if  necessary,  it  should  be  sealed  with  hot 
wax.  The  interior  of  the  band  and  surface  of  the  dowel  should  then  be 
covered  with  a  thin  film  of  melted  wax,  to  facilitate  its  removal  from, 
and  admit  of  its  accurate  readjustment  to,  the  model. 


230 


This  is  of  paramount  importance  in  this  class  of  work,  because  of 
the  necessity  for  frequently  trying  to  place  on  the  model  during  the  con- 
struction of  the  crown,  and  particularly  in  those  cases  requiring  a  resto- 
ration of  occlusion. 

The    facing   should  be    selected    in    accordance 
facing.  with  the  requirements  of  color  and  size,  and  ground 

to  conform  with  the  desired  shape  and  character- 
istics. As  the  color  is  more  likely  to  be  slightly  bleached  instead  of  be- 
coming darker,  if  any  variation  is  necessary  or  unavoidable,  it  should 
invariably  be  darker  than  lighter,  though  the  best  makes  of  porcelain 
teeth  rarely  change  to  any  appreciable  extent  if  the  proper  make  and 
color  of  "body"  is  placed  back  of  them,  and  properly  fused. 

In  this  connection,  it  is  necessary  to  use  a  "body"  the  fusing  point 
of  which  will  not  affect  the  color  of  the, facing,  as  an  example  of  which 
the  use  of  the  higher  fusing  American  "bodies"  in  combination  with  the 
English  make  of  facings  will  entirely  destroy  the  color  of  the  latter. 


a^ 


c 


cl 


Fic]J&3. 


In  grinding  the  facing,  the  edge  of  the  cap  should  previously  be 
nicely  rounded  with  disks  (Fig.  183,  A),  and  the  cervical  end  of  the 
facing  then  ground  thin  to  admit  of  overlapping  upon  the  labial  or  buccal 
edge  of  the  band  without  causing  undue  prominence  at  this  point.  (Fig. 
183,  B.) 

This  is  necessary  as  a  means  of  bringing  the  edge  of  the  facing  into 
close  proximity  with  the  gum,  and  for  the  purpose  of  thus  affording  a 
mechanical  retention  to  the  porcelain  with  which  this  portion  of  the  band 
should  invariably  be  completely  covered. 

If  the  platinum  band  is  not  entirely  covered  upon  this  surface,  it 
will  always  show  through  the  thin  transparent  tissue,  and  occasion  the 
presentation  of  a  dark  blue  line,  at  this  point. 

As  this  is  a  decidedly  inartistic  and  undesirahle  feature,  and  as  there 
is  no  physical  union  hettveen  porcelain  and  platinum,  the  overlapping  of 
the  facing  affords  a  secure  mechanical  retention  for  a  sufficient  quan- 
tity of  porcelain  to  cover  this  portion  of  the  band  and  overcome  this  pos- 
sible objection,  and  result  in  a  smooth  flush  joint  in  the  finished  crown. 


231 

Wherever  it  is  desirable  to  retain  porcelain  in  contact  with  platinum, 
some  similar  means  of  affording  mechanical  retention  is  always  neces- 
sary, and  this  may  be  further  facilitated  by  allowing  a  very  slight  space 
to  exist  between  facing  and  cap.-     (Fig.  183,0.) 

When  the  facing  has  been  thus  properly  adapted,  it  should  be  sealed 
to  place  on  the  cap  with  adhesive  wax,  and  the  whole  then  detached 
from  the  model  and  inves<^ed. 

In    investing,    only   enough   material    should   be 
Tnoestment.  used  to  surround  the  crown  nicely  and  afford  suffi- 

cient strength  in  the  investment ;  and  when  the  ma- 
terial has  crystallized,  all  surplus  should  be  trimmed  away  until  the 
entire  lingual  surface  of  the  facing  is  freely  exposed.    (Fig.  184.) 

This  free  exposure  is  necessary  as  a  means  of  facilitating  the  solder- 
ing, and  it  may  be  made  without  increasing  the  danger  of  fracturing  the 
facing,  if  the  case  is  then  adequately  heated  before  attempting  to  solder. 


FicfJS^^ 


Before  heating  the  case  the  pins  should  he  bent 
Soldcrfnfl  Taclng.  dozvn  tozvard  the  porcelain  until  their  ends  may  be 
brought  into  absolute  contact  with  the  metal  parts. 
This  may  be  done  by  holding  the  facing  firmly  in  place  with  a  blunt- 
pointed  instrument  in  one  hand,  to  prevent  displacing  it,  while  another 
instrument,  held  in  the  other  hand,  may  be  placed  against  the  extreme 
ends  of  the  pins  and  sufficient  pressure  applied  to  bend  them  into  the 
<lesired  relation. 

While    it    is    always    desirable   to   get   the   pins 
interior  Crowns.       down  dose  to  the  facing,  and  thus  make  more  room 
for  the  porcelain,  and  still  have  an  equal  degree  of 
strength  in  their  attachment,  this  is  especially  indicated  in  the  construc- 
tion of  anterior  crowns. 

In  th€se  crowns  the  pins   should  be  bent  down  close  to  the  porce- 
lain,  and  their  ends  brought   into  contact   with   the   surplus  end  of  the 


dowel  at  a  point  as  close  to  the  floor  of  the  cap  as  possible  (Fig.  185,  A),. 
or  in  direct  contact  with  the  floor  itself.     (Fig.  185,  B.) 

This  is  important,  because  it  affords  opportunities  for  the  same  de- 
gree of  strength  in  their  union  with  the.  cap,  and  yet  adds  to  that  of  the 
crown  by  getting  the  metal  parts  out  of  the  way,  so  that  they  will  not 
divide  the  porcelain  through  the  center,  or  interfere  with  the  proper  and 
desired  contour  of  the  lingual  surface. 

In  cases  where  the  ends  of  the  pins  will  not  reach  to  the  floor,  or 
dowel,  the  space  between  them  and  the  floor,  after  being  bent  down  to- 
ward the  porcelain,  may  be  filled  in  with  one  or  two  thicknesses  o£ 
platinum  plate,  or  wire,  if  necessary,  until  continuous  contact  may  be 
secured,  as  illustrated  in  Fig.  185,  C.  The  finished  crown,  showing  the 
possibilities  of  contour,  strength  and  artistic  effect,  is  illustrated  in  Fig. 
j85,D. 


U 


f/<f.  185. 


As  there  is  no  physical  union  between  porcelain 
Bicuspid  Crowns.  and  platinum,  in  the  construction  of  bicuspid 
crowns,  it  is  not  only  desirable  to  make  as  much 
spa^^eTor  the  porcelain  which  is  to  form  the  entire  lingual  surface  of  the 
crown,  as  possible,  but  it  is  also  often  necessary  to  provide  some  means 
for  supporting  it  against  any  possible  line  of  cleavage,  in  order  to  pre- 
clude subsequent  fracturing  of  this  mass  of  porcelain  from  the  stress  of 
mastication. 

This  support  to  the  porcelain,  and  destruction  of  the  line  of  cleav- 
age, may  be  best  and  most  easily  accomplished  by  soldering  a  narrow 
band  of  platinum  to  the  floor  of  the  cap,  about  one-sixteenth  of  an  inch 
inside  of  the  edge  of  the  band.  This  shoidd  he  fitted  before  heating  the 
case,  and  may  be  attached  at  the  time  of  soldering  the  facing,  and  its  pres- 
ence thus  forms  a  cup-shaped  support  which  admirably  answers  the  pur- 


pose  for  which  it  is  intended,  without  showing^  through,  or  materially 
weakening-,  the  porcelain.     (Fig.  i86.  A.)  '  >j    , 

Another  means  of  accomplishing  the  same  end  has  been  suggested 
by  Dr.  Capon,  and  consists  in  adapting  and  attaching  a  band  around  the 
outside  of  the  entire  lingual  surface  of  the  cap,  from  one  side  of  the  fac- 
ing to  the  other,  and  projecting  about  one-sixteenth  of  an  inch  beyond  the 
floor.  (Fig.  i86,  B.)  This  method  retains  and  supports  the  porcelain  in 
a  splendid  manner,  but  is  much  more  difficult  to  adapt,  and  detracts  some- 
what from  the  artistic  efifect  obtained  in  the  finislied  crown. 

The  same  result  may  also  be  obtained  by  attaching  a  small  vertical 
extension  of  round  platinum  wire  to  the  immediate  center  of  the  lingual 
portion  of  the  cap.  (Fig.  i86,  C.)  Or,  when  two  dowels  are  used,  the 
surplus  end  of  the  lingual  one  may  be  so  employed.     (Fig.  i86,  D.) 

Unless  in  the  latter  instance  this  is  somewhat  difficult  to  hold  in  its 
proper  place  while   soldering,   and  may  prove  an   element  of   weakness 


IX. 


c 

Fi<j.  18  6. 


d 


instead  of  strength,  if  not  properly  adjusted.  When  this  procedure  is 
observed  in  either  instance  the  extension  of  wire  should  be  in  \}a^- exact 
center,  not  project  over  one-sixteenth  of  an  inch  beyond  the  floor,  and 
the  extreme  end  always  well  rounded.  The  finished  crown  is  illustrated 
in  Fig.  1 86,  E. 

In    the     construction    of     molar    crowns,     two 
niOlar  0rown$.        methods  are  employed.     One  consists  in  using  a  "fac- 
ing and  observing  similar  details  to  those  indicated 
in  the  construction  of  bicuspids,  and  the  other  in  making  the  cap,  and 
building  the  entire  crown  of  porcelain  without  a  facing. 

While  it  is  true  that  the  requirements  of  color 

Ulitb  Tacing.  are  not  quite  so  important  in  molars,  the  best  results 

will  usually  be  obtained  from  the  use  of    a    facing 

whenever  possible,  for  the  reason  that  both  the  form  and  color  of  the 

visible  parts  of  the  crown  are  obtained  and  preserved  in  the  facing. 


234 

When  a  facing  is  used,  the  construction  should  be  made,  as  indi- 
cated for  bicuspid  crowns,  and  illustrated  in  Fig,  187,  A,  and  Fig.  187, 
B  shows  the  finished  crown. 

In  very  close  "bites"  the  use  of  a  facing  may 
UlitbOtlt  Tacing.        often  be   contraindicated,  and  the    best    results  ob- 
tained by  simply  making  the  cap  and  forming  the 
entire  crown  with  porcelain.     For  such  cases  the  porcelain  should  be  sup- 
ported by  any  of  the  means  indicated,  the  variations  of  which,  together 
with  the  finished  crown,  are  illustrated  in  Fig.  188. 


a 


Fiq.187. 


Additional  mechanical  means  for  obtaining,  or  aiding  in,  the  attach- 
ment of  the  porcelain  to  the  cap  may  also  be  secured  in  any  of  these  vari- 
ous styles  of  construction,  by  roughening  or  spurring  the  surface  of  the 
platinum  with  a  sharp-pointed  instrument.  This  latter  method  is  em- 
ployed exclusively  by  some,  and  may  serve  the  purpose  in  large  crowns, 


F/q.l8d, 


where  considerable  surface   is  exposed,  without  being  supplemented  by 
any  of  the  former  means. 

Uaridtions  in  Construction. 

Because  of  the  acknowledged  advantages  of  a  band,  the  foregoing" 
style  of  construction  has  been  given  precedence,  and  designated  as  the 
typical  one;  yet,  while  it  is  true  that  crowns  so  made  are  perhaps  more 
universally  applicable,  and  productive  of  more  permanent  results,  it  is 
also  true  that  there  are  many  variations  of  methods  of  more  or  less  value, 
the  employment  of  many  of  which  may  be  frequently  indicated. 


235 

Rccnforced  €ap$. 

As  inherent  strength  in  the  metal  parts  has  already  been  claimed  as 
a  prerequisite  in  this  work,  one  of  the  most  useful  variations  in  the  con- 
struction is  to  be  obtained  by  reenforcing  the  cap  in  a  manner  similar  to 
that  previously  recommended  in  the  construction  of  crowns  with  the  so- 
called  saddle-back  teeth. 

Such  a  procedure  imparts  to  the  finished  porcelain  crown  a  degree 
of  strength  which  is  appreciably  valuable  in  many  cases ;  particularly  in 
bicuspid  crowns,  and  in  those  cases  where  the  crown  is  not  supported  by 
adjacent  teeth  on  one  or  both  sides,  and  where  the  absence  of  some  of 
the  opposing  teeth  necessitate  more  than  average  occluding  stress. 

This  increased  strength  may  be  secured  by  allowing  the  floor  to  pro- 
ject slightly  beyond  the  band  upon  the  approximal  and  lingual  surfaces, 
and  then  filling  in  the  shoulder  so  formed  with  platinum  solder  until 
smooth  and  flush.    The  additional  thickness  of  a  cap  so  made  further  pre- 


cludes the  possibility  of  subsequent  irritation  to  the  surrounding  tissue  by 
afifording  a  heavier,  smoother  and  more  roimding  edge. 

In  accomplishing  this  result,  the  procedure  inci- 
PfOCCdurc.  dent  to  the  fitting  of  the  band  and  construction  of 

the  cap  is  identical  with  that  indicated  in  the  preced- 
ing method,  except  that  platinum  solder  should  be  used. 

When  the  floor  has  been  attached  to  the  band,  the  surplus  should  be 
trimmed  away  until  a  projecting  edge,  from  1/16  to  1/32  of  an  inch, 
remains  upon  the  approximal  and  lingual  surfaces.  The  labial  or  buccal 
surface,  however,  must  be  trimmed  flush  and  even  with  the  band,  in  order 
to  prevent  an  undue  prominence  of  the  neck  of  the  facing,  and  to  admit 
of  properly  overlapping  it  upon  this  surface  of  the  band,  both  features 
of  which  are  illustrated  in  Fig.  189,  A. 

The  slight  shoulder  so  formed  should  be  filled  in  with  25  per  cent 
platinum  solder,  until  flush  and  even  with  the  band,  the  edge  then  nicely 
rounded  and  the  dowel  fitted  and  soldered  as  usual.     (Fig.  189,  B.) 

The  completed  cap,  with  the  proper  relation  of  the  facing,  is  shown 
in  Fig.  189,  C,  and  the  finished  crown,  with  its  apparent  advantages,  in 
Fig.  189,  D. 


236  ■ 
Without  Bana. 

That  style  of  construction  which  involves  simply  the  adaptation  of 
a  metal  floor  or  base  to  the  end  of  the  root,  and  the  attachment  of  a  dOwel 
and  facing  thereto,  and  which  has  previously  been  designated  as  the 
-"plate  and  dowel"  crown,  is  equally  as  applicable  to  porcelain  work  as 
to  gold  work. 

The  indications  and  general  principles,  and  the 
PfOCCdurc.  detail  of  procedure  incident  to  the  requirements  of 

root  preparation,  and  the  construction  of  the  base 
of  the  crown,  are  identically  the  same  as  previously  outlined.  The  only 
exception  is  the  variation  which  the  completion  of  the  crown  with  porce- 
lain "body"  instead  of  gold  solder  demands,  and  which  includes  the  use 
of  platinum  and  high-grade  solder. 


Fici.  190. 


Wherever  a  band  is  not  desirable,  for  any  rea- 

PlaU  and  Dowel.       son,  or  where  its  use  may  be  contraindicated,  and  the 

preference  given  to  this  style  of  construction,  a  plate 

of  platinum  about  36  gauge  should  be  adapted  to  the  end  of  the  root,  by 

burnishing  or  swaging,  as  indicated  in  Chapter  X. 

The  dowel  should  then  be  soldered;  the  cap  again  adjusted  to  the 
root,  and  reburnished  and  properly  trimmed  around  the  edge,  the  models 
secured,  and  the  facing  attached  by  observing  the  requirements  indicated 
in  the  immediately  preceding  style  of  construction,  as  are  consecutively 
illustrated  in  Fig.  190.  If  the  presence  of  this  thin  plate  of  platinum 
should  be  objectionable  or  conspicuous,  it  may  be  afterward  removed 
by  destroying  its  attachment  to  the  dowel  with  a  small  round  bur,  care- 
fully inserting  the  edge  of  a  thin  knife  blade  between  it  and  the  porcelain 
on  the  lingual  surface,  and  gently  lifting  it  away  from  the  base  of  the 
crown.  A  slight  deepening  of  the  canal,  or  shortening  of  the  dowel,  will 
allow  for  its  absence,  and  admit  of  placing  the  crown  in  close  proximity 
with  the  root. 


237 
Partial  Bands. 

The  employment  of  a  partial  ijand  encircling  only  the  approximal 
and  lingual  sides  of  the  root,  as  a  means  of  increasing  the  stability  of 
the  attachment  of  the  crown,  may  also  be  made  in  a  manner  similar  to 
that  already  mentioned. 

As  this  style  of  construction  serves  to  fortify  the  crown  against  stress 
in  the  direction  in  which  it  is  usually  imposed,  and  also  renders  this  por- 
ton  of  the  joint  between  crown  and  root  more  or  less  immune  to  the 
jjenetration  of  secretions,  it  at  once  recommends  itself  as  a  useful  practice, 
especially  indicated  on  the  six  anterior  teeth,  where  the  root  is  allowed 
to  project  slightly  beyond  the  gum  line  on  the  lingual  side. 


/\ 


Fi<jJ9L 


The  effect  of  a  partial  band  to  serve  such  pur- 

Proccdwrc.  poses  ma}-  be  obtained  with  the  greatest  degree  of 

facility  by  allowing  a  sufficient  surplus  of  the  plate 

to  extend  beyond  the  root  on  this  surface,  until  the  adaptation  of  ihe  base 

has  been  secured,  and  the  dowel  soldered. 

The  cap  may  now  be  adjusted  to  position  on  the  root,  where  it  is 
held  firmly  by  the  presence  of  the  dowel,  and  this  surplus  edge  then  bur- 
nished up  close  to  the  surface  of  the  root,  and  finally  trimmed  to  follow 
the  curvature  of  the  gum. 

A  surplus  sufficient  to  admit  of  reaching  the  gum  line,  and  passing 
just  a  bit  beneath  it,  should  always  be  allowed  to  remain,  and  if  the 
accurate  burnishing  of  this  upturned  edge  is  made  difficult  because  of 
the  length  of  the  root,  a  slight  incision  through  the  surplus  edge  of  the 
plate  at  the  center  of  the  lingual  surface  will  facilitate  the  possible  adapta- 
tion. This  may  be  subsequently  soldered,  either  before  or  after  the  im- 
pression has  been  taken,  but  should  always  be  done  before  the  porcelain 


238 

is  applied.     More  than  one  incision  may  be  sometimes  indicated,  and  are 
permissible  when  necessar}^ 

The  various  steps  in  this  style  of  construction  are  consecutively  illus- 
trated in  Fig.  191. 

Jacket  Crowns. 

The  principles  involved  in  the  so-called  "jacket"  style  of  crown  con- 
struction, as  applied  to  both  gold  and  porcelain  work,  have  been  else- 
where considered,  together  with  the  indications,  advantages  and  disad- 
vantages governing  their  application. 

The  practicability  of  these  crowns,  however,  when  made  in  com- 
bination with  porcelain,  is  apparently  a  question  of  much  dispute,  and 
has  continued  to  be  since  the  method,  which  was  the  primitive  effort  in 
the  line  of  constructing  porcelain  crowns  in  combination  with  platinum, 
was  first  suggested  by  Dr.  C.  H.  Land. 

The  advocates  of  this  style  of  construction  claim  that  it  is  more  or 
less  universally  indicated  in  restoring  the  crowns  of  the  six  anterior  teeth, 
upper  and  lower ;  and  that  the  principal  advantage  lies  in  the  conservation 
of  tooth  structure,  and  the  preservation  of  the  pulp. 

While  both  of  these  considerations  are  always  of  material  significance 
to  the  conscientious  operator,  and  should  be  observed  wherever  possible, 
still  they  do  not  constitute  the  complete  maximum  of  requirements  of 
crown  construction  and  application,  even  when  combined  with  the  highest 
esthetic  possibilities,  because  the  requirement  of  strength  is,  of  course, 
of  equal  importance,  having  so  great  an  influence  upon  the  serviceability 
and  permanency  of  the  work. 

In  view  of  this  fact,  and  also  that  the  projecting  end  of  the  crown 
of  the  natural  tooth,  which  is  to  be  telescoped  by  the  cap  or  "jacket,"  as 
a  means  of  affording  attachment  for  the  artificial  crown,  is  allowed  to 
remain,  or  is  preserved,  at  the  expense  of  the  thickness  of  porcelain  which 
may  be  subsequently  used  in  the  construction  of  the  crown ;  and,  because 
of  the  friable  nature  of  porcelain,  particularly  when  used  in  small  quan- 
tity, this  style  of  construction  is  not  to  be  recommended  as  a  general  or 
conservative  practice,  and  is  by  no  means  universally  applicable,  if  the 
most  permanent  results  are  desired. 

In  this  connection,  it  seems  more  than  probable  that  a  large  per- 
centage of  the  early  failures  which  marked  the  advent  of  the  porcelain 
crown  constructed  for  the  individual  case,  and  retarded  the  development 
of  this  work,  may  be  attributed  as  much  to  the  method  of  construction  as 
to  the  use  of  the  lozv  fusing  bodies,  which  were  formerly  employed. 

Aside  from  the  inherent  weakness,  which  adequate  accommodation 


239 

for  the  root  in  the  body  of  the  crown  demands,  the  artistic  possibiHties 
are  also  often  somewhat  hampered  by  the  more  or  less  clumsy  appear- 
ance of  the  finished  crown. 

Whenever  on   adequate  length  of  the  adjacent 
Indications  for         teeth,  and  a  favorable  occlusion,  will  admit  of  over- 
Porcdaln  jackets,      coming  these  objectionable  features,  and  securing  a 
maximum  degree  of  strength,  jacket  crowns  may  be 
porcelain,     producing     serviceable     and     artistic 


with 


constructed 
restorations. 

In   the   application   of   this   style  of  crown,   the 
Procedure.  remaining  natural  crown  should  be  favorably  shaped 

to  admit  of  the  accurate  adaptation  of  the  jacket,  and 
of  the  proper  alignment  of  the  facing,  as  indicated  in  the  previous  con- 
sideration, and  illustrated  in  Fig.  192,  A. 


« 


The  measurement  should  be  taken  and  a  band  of  about  36  gauge 
platinum,  wide  enough  to  encompass  the  entire  remaining  natural  crown, 
then  made.  The  overlapping  of  the  ends  in  this  instance  is  not  always 
advisable,  because  of  the  impediment  offered  to  the  burnishing  by  such 
additional  stiffness. 

When  this  has  been  accurately  trimmed  and  fitted  at  the  cervical 
edge,  a  cut  in  each  approximal  side  of  the  band,  beginning  at  the  incisal 
and  extending  well  toward  the  cervical  edge,  will  facilitate  the  subsequent 
burnishing  of  the  platinum  into  a  close  conformation  with  the  root,  A 
blunt  piece  of  wood  and  a  light  mallet,  or  a  smooth  foot-plugger  in  an 
automatic  mallet  may  be  found  useful  in  this  procedure,  but  care  should 
be  exercised  to  avoid  drawing  the  cap  down  from  its  proper  cervical 
relation. 

The  edges  should  now  be  pinched  together  with  pliers  around  the 
incisal  end  of  the  root  until  in  close  contact,  the  cap  then  removed,  the 
surplus  trimmed  away,  and  the  joints  soldered.     Pure  gold  will  answer 


24P 

nicely  for  this  purpose,  if  used  sparingly  and  properly  fused,  though  plati- 
num solder  is  preferable. 

Platinum  foil,  No.  60  or  120,  may  often  be  used  in  securing  the 
proper  adaptation  around  the  cervix,  and  slightly  beneath  the  free  mar- 
gin of  the  gum,  to  which  point  it  should  be  carried,  because  of  the  greater 
facility  with  which  it  may  be  even  more  closely  adapted;  and  extreme 
thinness  of  the  cap,  on  the  labial  surface,  at  least,  is  also  advantageous 
to  the  subsequent  adjustment  of  the  facing.  In  the  use  of  the  foil,  how- 
ever, when  the  proper  adaptation  has  been  secured  by  burnishing,  with 
the  surplus  overlapped  upon  the  approximal  and  lingual  surfaces,  the 
cap  should  then  be  slightly  re-inforced  with  platinum  solder,  or  pure  gold 
thoroughly  fused. 

The  best  results  are  doubtless  to  be  obtained,  as  a  general  practice, 
from  the  use  of  the  heavier  cap,  and  while  pure  platinum  is  not  as  soft 
and  malleable  as  pure  gold,  if  the  piece  is  well  annealed  in  the  porcelain 
furnace,  as  recommended,  no  great  difficulty  will  be  experienced  in  adapt- 
ing platinum  of  36  gauge  to  the  requirements  of  these  cases.  If  prefer- 
able, the  adaptation  may  be  secured  by  taking  an  impression  of  the  end 
of  the  root,  making  dies  and  swaging,  as  previously  described. 

The  entire  surface  of  the  cap,  however  made  (Fig.  192,  B),  should 
now  be  slightly  roughened  with  a  sharp  chisel,  or  other  convenient  instru- 
ment, to  facilitate  the  attachment  of  the  porcelain,  and  the  impression 
taken  with  it  in  position  on  the  root.  Before  filling  the  impression,  the 
cap  should  be  filled  with  wax  to  facilitate  its  subsequent  removal  from 
the  model. 

A  very  thin  facing  (Fig.  192,  C)  of  the  proper  size  and  color  should 
now  be  selected  and  ground  to  its  proper  adjustment.  This  sometimes 
requires  that  the  entire  lingual  surface,  including  pins,  be  ground  away 
until  only  a  very  thin  veneer  remains,  but  it  is  best  to  allow  the  pins  to 
remain  also,  if  possible,  because  of  the  advantage  to  be  derived  from 
their  presence  in  securely  sustaining  the  relation  of  the  facing  to  the  cap, 
by  bringing  them  in  contact  and  soldering,  previous  to  applying  the  por- 
celain.    (Fig.  192,  D.) 

Where  it  becomes  necessary  to  grind  the  pins  away  entirely,  the  dif- 
ficulty of  sustaining  the  veneer  in  its  relation  to  the  cap  during  the  appli- 
cation and  fusing  of  the  "body"  is,  of  course,  increased,  and  extreme  care 
is  necessary  in  heating  the  case,  because  of  the  possible  expansion  incident 
to  too  rapid  heating ;  and  in  fusing,  because  of  the  shrinkage,  each  of 
which  may  result  in  a  displacement. 

This  procedure  may  be  facilitated  by  first  covering  the  cap  with  a 
thin  layer  of  "body"  and  fusing  it  until  the  particles  are  well  coalesced, 
without  presenting  a  glazed  surface.     This  then  admits  of  a  more  ready 


241 


and  secure  attachment  of  the  veneer  to  the  cap  by  holding  it  in  place 
and  packing  tliinly  mixed  liod>-  into  the  space  between  it  and  the  cap, 
until  it  is  retained  in  position  by  the  adhesive  properties  of  the  bodv  after 
the  moisture  has  been  evaporated,  when  it  is  ready  for  the  final  attachment 
to  be  obtained  by  the  fusion  of  the  porcelain.  Fig.  192,  E,  illustrates  the 
finished  crown. 

A    method    of    veneering    platinum    and    gold 
UarlatlOlt  of  method,     crowns  constructed  in  the  ordinary  manner,  excepting 

that  tlic  dimensions  arc  reduced  enough  to  admit  of 
the  presence  of  a  covering  of  porcelain,  which  is  retained  in  contact  with 
the  metal  by  roughening  the  surface,  is  recommended  by  Dr.  George  Evans 
.and  others,  as  a  means  of  securing  the  presentation" of  a  more  esthetic 
effect,  combined  with  the  advantages  of  a  metal  crown. 

As  thin  layers  of  porcelain,  whether  of  the  high  or  low  fusing  variety 
■do  not  possess  strength,  and  as  there  is  no  physieal  or  nwh-cidar  union, 
between  porcelain  and  platinum,  or  gold,  the  method  is  not  considered  to 
.  be  a  safe  or  reliable  one. 

Where  the  jacket  crown  is  to  be  employed  in  combination  with  porce- 
1am,  the  strength  of  the  body  itself,  and  the  integrity  of  the  attachment 
between  it  and  the  metal  parts,  both  of  which  are  essential  to  the  dura- 
bihty  of  the  finished  crown,  will  increase  in  proportion  to  the  diminution 
of  the  root,  the  quantity  of  porcelain  thus  accommodated,  and  the  deo-ree 
ot  mechanical  attachment  for  it,  which  is  to  be  obtained  bv  rouo-henlno- 
and  serratmg  all  surfaces  of  the  metal  which  are  to  be  covered  with  tlie 
"body." 

On  the  other  hand,  it  must,  of  course,  be  remembered  that  the  de-ree 
of  integrity  m  the  attachment  of  the  finished  crown  to  the  root  will  increase 
in  proportion  to  the  extent  of  tooth  structure  which  is  allowed  to  remain 
and  which  may  be  telescoped  by  the  cap. 


Use  Of  m  Hwii  ana  Eogan  £rown$. 

Ready-made  porcelain  crowns,  such  as  the  Davis  and  Logan  designs, 
may  sometimes  be  employed  to  good  advantage  in  porcelain  work  for  the 
six  anterior  teeth,  by  combining  them  with  a  a  platinum  plate  or  cap,  as 
a  means  of  securing  accuracy  in  their  adaptation  and  permanency  in  their 
attachment  to  the  root. 

The  advantages  to  be  obtained  in  the  use  of  these 

nmntms,  crowns  in  this  work  lie  in  their  artistic  form,  their 

unexcelled  strength,  and  the  greater  degree  of  trans- 

]ucency  which  the  finished  crown  will  possess,  as  a  result  of  the  absence 


242 

of  an  additional  layer  of  either  metal  or  porcelain  placed  on  the  back  of 
the  original  crown. 

While  their  artistic  shape  is  not  to  be  disputed,  the  experienced  por- 
celain worker,  with  a  knowledge  of  tooth-form,  will  have  no  difficulty 
in  building  the  body  to  an  equally  artistic  outline,  where  a  facing  is  used, 
so  this  feature  is  to  be  seriously  regarded  as  a  consideration  only  as  a. 
means  of  doing  without  the  knowledge,  and  avoiding  the  small  amount 
of  time  and  work  thus  involved. 

The  inherent  strength  of  the  porcelain  of  which  these  crowns  are 
made,  which  is  obtained  from  the  high  fusing  character  of  the  "body,"" 
and  from  its  then  being  properly  packed  and  fused,  is  doubtless  greater 
than  the  strength  of  the  porcelain  part  of  a  crown  constructed  with  a 
facing.  Hence,  this  feature  must  be  regarded  in  the  light  of  an  advantage 
of  importance,  and  yet,  where  a  simple  facing  is  used,  sufficient  strength 
may  ordinarily  be  obtained  by  securely  attaching  it  to  the  cap,  using  a 
high-grade  "body,"  and  properly  packing  and  fusing  it. 

The  greater  degree  of  translucency  is  indisputably  true,  and  consti- 
tutes an  advantage  of  inestimable  value  in  many  cases,  particularly  where 
the  color  is  extremely  difficult  to  match.  While  the  texture  of  an  ordinary 
facing  may  be  practically  the  same  as  that  of  these  crowns,  and  it  may 
primarily  possess  the  same  degree  of  translucency,  yet  this  important  fea- 
ture is,  nevertheless,  destroyed  to  some  extent  even  by  the  presence  of  a 
backing  of  porcelain,  of  nearly,  if  not  quite,  the  same  color.  This  is  due 
to  the  dividing  line  between,  and  the  difference  in  the  density  of,  the  two 
bodies. 

These  features  of  strength  and  translucency  are  so  important  as  tO' 
indicate  the  practicability  and  warrant  the  use  of  these  crowns  in  many 
cases,  perhaps,  in  preference  to  any  other  style  of  construction,  where  a 
good  selection  may  be  obtained. 

The  principal  disadvantages  lie  in  the  fact  that 

Di$adO{intad($«  one  is  confined  to  a  more  or  less  limited  selection,  and 
that  the  opportunities  are  greater  for  securing  a  bet- 
ter choice  of  facings  than  of  crowns  because  of  the  latter  being  limited 
to  a  few  dozen  moulds,  as  compared  with  the  several  hundred  in  which 
the  facings  are  made ;  also  the  more  intricate  procedure,  and  greater  length 
of  time  consumed,  in  grinding  the  crown  to  a  proper  adjustment  and  rela- 
tion as  compared  with  the  facing. 

Because   of   the   greater    facility   with   which    a 

Jlpplication  OT         crown  with  a  separate  dowel  may  be  adapted  to  the 
the  Davl$  Crown.       root,  the  Davis  crown  will  be  found  more  generally 
useful  and  applicable  in  this  style  of  construction. 

The  accompanying  dowel,  however,  is  useless,  and  must  be  replaced 


243 

witli  one  of  iridio-platinum,  because  the  so-called  German  silver  alloys 
will  scarcely  withstand  the  degree  of  heat  necessary  to  subsequently  fuse 
the  porcelain,  and  the  latter  will  not  become  attached,  or  even  fuse  down 
close,  to  these  alloys. 

In  the  application  of  this  style  of  crown  with 

mith  Band.  a  band,  the  root  should  be  prepared,  the  cap  made, 

the  dowel  attached,  and  the  impression  taken,  in  exact 

accordance  with  the  requirements   indicated   for  the  "band  and   dowel" 

style    of    construction    with    porcelain,     at    the     beginning    of    this 

chapter. 

When  the  model  has  been  secured,  the  cap  should  be  detached  there- 
from, then  replaced,  and  the  crown  selected. 

The  surplus  end  of  the  dowel  should  now  be  cut  away  until  only 
so  much  remains  as  will  be  accommodated  by  the  depth  of  the  countersunk 
cavity  in  the  crown,  and  the  latter  should  be  ground  to  the  proper  and 
required  adaptation  with  the  cap  and  the  adjacent  and  occluding  teeth. 


In  this  procedure  the  approximal  sides  should  be  ground  so  as  to 
admit  of  the  overlapping  of  the  labial  and  lingual  edge  of  the  crown  upon 
the  cap.  (Fig.  193,  A.)  This  is  essential  for  the  purpose  of  bringing 
the  edges  of  the  crown  into  close  proximity  with  the  gufti  and  of  retaining 
the  porcelain  which  is  to  be  subsequently  applied  to  cover  the  band. 

Owing  to  the  shrinkage  of  porcelain,  it  is  impossible  to  get  enough 
body  between  the  crown  and  cap  in  the  first  or  primary  "bake"  to  com- 
pletely fill  the  space.  This  would  result  in  an  element  of  weakness,  of 
course,  in  the  finished  crown,  and  may  be  overcome  by  further  grinding 
away  the  approximal  surfaces  of  the  crown,  so  as  to  afford  opportunity 
for  the  admission  of  a  second  application  of  "body,"  which  may  fill  all 
crevices  caused  by  the  shrinkage  of  the  first.     (Fig.  193,  B.) 

When  the  grinding  of  the  crown  has  thus  been  completed,  it  should 
be  attached  to  the  cap  by  filling  the  countersunk  cavity  in  its  body  with 


244 

thin,  well  mixed  porcelain,  and  then  gently  forcing  it  to  place  while  on 
the  model.  The  latter  should  now  be  gently  tapped  with  an  instrument 
several  times  to  pack  the  porcelain  densely  around  the  dowel,  and  in  the 
space,  and  it  should  then  be  allowed  to  dry  until  all  of  the  moisture  is 
thoroughly  evaporated. 

The  crown  should  now  be  gentl}^  removed  from  the  model,  adjusted 
to  a  proper  support,  and  given  the  primary  "bake,"  and  subsequently  the 
final  one,  in  accordance  with  the  requirements  which  will  be  considered 
later.     The  completed  crown  is  illustrated  in  Fig.  193,  C. 

When  it  is  desirable  to  construct  the  crown  by 

mitbOUt  Band.         this  method  zvithoiit  a  band,  the  foregoing  detail  is 

identical  zvith  the  requirements,  after  the  "plate  and 

dowel"  have  been  properly  adapted  to  the  root  and  the  impression  taken 


Ficj.  19^. 


and  model  secured,  which  procedure  has  been  previously  considered  in 
its  special  application  to  porcelain  work  in  this  chapter.  The  various 
steps  in  this  style  of  construction  are  illustrated  in  Fig.  194. 

Tlie  Logan  crown  may  be  used  in  similar  man- 
Jlpplkation  of  ner,  with  either  a  band  or  simple  plate,  and  the  differ- 

tbC  Cogan  €rown.      ence  in  the  procedure  incident  to  its  employment  lies 
in  the  absence  of  any  necessity  for  using  other  than 
the  original  dowel,  which  is  of  platinum  and  which  constitutes  an  insepar- 
able part  of  the  crown. 

■  The  presence  of  an  inseparable  dowel  in  this  connection,  however, 
adds  somewhat  to  the  detail  involved  in  grinding  the  crown  to  the  required 
adaptation  with  the  cap  or  plate,  and  necessitates  subjecting  the  porcelain 


^'45 

to  the  heat  of  solderino;  in  attaching-  it  thereto,  which,  of  course,  is  not  true 
in  the  use  of  tlie  Davis  crown. 

In  the  application  of  this  crown  in  comhination 
Procedure.  with  porcelain  and  a  platinum  cap  or  plate,  the  same 

detail  as  indicated  in  connection  with  the  use  of  ^old 
should  be  observed. 


FJq.  195, 


The  base  should  be  constructed  of  platinum  of  the  same  gauge  as 
for  the  Davis  crown,  and  the  temporary  dowel  should  be  adjusted,  the 
impression  taken,  and  the  model  secured  in  accordance  with  the  detail 
previously  outlined  in  the  consideration  of  this  style  of  crown  in  com- 
bination with  ofold. 


/>y.  196. 


The  crown  should  be  then  selected,  ground  as  thus  indicated  (Fig. 
195,  A),  attached  to  the  base  with  a  minute  quantity  of  adhesive  wax^ 
removed  from  the  model,  invested,  and  the  relation  between  the  base  and 
dowel  permanently  sustained  with  a  small  quantity  of  pure  gold,  to  pre- 
clude any  possible  change  which  might  result  from  the  shrinkage  of 
Dorcelain. 


246 

The  soldering  may  be  done  with  greater  facility  by  covering  the  entire 
crown  with  investment  material,  leaving  only  the  surface  of  the  base, 
which  comes  in  contact  with  the  root  and  the  dowel,  exposed.  ^Fig.  196.) 
Considerable  care  must  be  exercised  in  this  procedure,  however,  to  prevent 
fracturing  the  porcelain,  which  can  only  be  avoided  by  thoroughly  heating 
the  latter  before  attempting  to  solder.  This  space  between  base  and  crown 
may  then  be  filled  with  porcelain  "body"  and  fused,  and  the  finished  crown 
is  illustrated  in  Fig.  195,  B. 


Gomposition,  ebaracteristics  and  manipulation 
of  Porcelain  Bodies. 


CHAPTER  XIII. 

Porcelain  Compounds:  Composition;  Silica,  Feldspar,  Kaolin,  "Flux,"  Col- 
oring Matter.  "High  and  Low"  Fusing  "Bodies" :  Comparative  Advantages. 
Shrinkage,  Fusing  Points.  "Gum  Enamel"  "Bodies."  Requirements  for 
Crown  and  Bridgework.  Manipulation  of  Body:  Preparation  of  Crown,  Se- 
lection of  Color.  Mixmg  "Bodj',"  Applying  and  Building.  One  Grade  of 
"Body."  Variations  in  Shading;  Use  of  Oil  Colors;  Contouring  and  Carving. 
Primary  "Bake."  Final  "Bake."  "Foundation"  and  "Enamel"  "Bodies." 
Precautions  Incident  to  Fusing.  Supporting  Crown  in  Furnace.  Placing  Crown 
in  Furnace.  Heating  Furnace.  Fusing:  Tests,  Porosity.  Furnaces:  Electric 
Furnaces,  Gasoline  Furnaces,  Gas  Furnaces. 


Porcelain  Compounds. 

With  the  rapid  development  of  this  class  of  work,  a  demand  has 
been  created  for  the  production  of  porcelain  compounds  which  possess 
qualities  better  suited  to  the  requirements  of  manipulation  and  color  than 
was  characteristic  of  those  which  were  formerly  used,  and  which  had 
been  especially  prepared  for  continuous  gum  work. 

This  latter  grade  of  material,  as  originally  compounded  by  Dr.  John 
Allen,  and  later  by  Dr.  S.  L.  Close,  in  the  absence  of  anything  better, 
was  quite  commonly  used,  and,  when  more  finely  pulverized  to  admit 
of  being  carved  and  fused  vv^ith  greater  accuracy,  it  served  the  pur- 
pose so  well  as  to  be,  to  a  great  extent,  responsible  for  the  growth  and 
development  of  this  class  of  work  to  the  degree  of  its  present  successful 
attainment. 

As  it  was  prepared  in  only  one  grade  and  color,  however,  the  de- 


248 

mands  created  by  the  possibilities  of  this  work  soon  induced  other  man- 
ufacturers to  so  alter  and  improve  upon  these  materials  as  to  furnish 
compounds  which  would  be  somewhat  less  refractory,  and  which  would 
more  nearly  meet  the  requirements,  with  the  result  that  several  products 
are  now  prepared  in  different  grades  and  varying  colors. 

These  various  compounds  are  supplied  in  powder 
Composition.  form,  and  are  known  as  "bodies,"    "enamels,"    and 

"gum  enamels."  They  are  composed  of  silica,  feld- 
spar, kaolin  and  a  suitable  "flux,"  and  are  colored,  or  tinted,  with  metals 
or  metallic  oxides.  ^ 

Silica  is  the  dioJcide  of  silicon,  a  very  refractory 
Silica.  and  practically  infusible  substance  found  in  the  form 

of  agate  and  flint.  It  is  the  base  of  all  true  porce- 
lain "bodies,"  and  imparts  structural  strength  to  them. 

Feldspar  is  a   double  silicate  of  aluminum  and 
Tddspaf.  potassium.     This   material  is  somewhat  less  refrac- 

tory than  silica,  and  is  incorporated  for  the  purpose 
of  imparting  stability  to,  and  increasing  the  translucency  of,  the  com- 
pound. 

Kaolin   is   the   hydrated   silicate    of    aluminum. 
Kaolin.  This  is  a  very  fine  grade  of  clay,  and  is  a  most  essen- 

tial ingredient,  being  incorporated  for  the  purpose 
of  imparting  stability  of  form  by  holding  the  particles  together,  and  thus 
facilitating  the  moulding  and  carving  of  the  mass  into  the  desired  shape. 

The  "flux"  is  usually  composed  of  the  carbon- 
"TIUX."  ates  of  the  alkaline  metals,   sodium  and  potassium, 

though  in  some  classes  of  compounds  the  oxide  of 
lead  is  also  much  used. 

The  quantity  and  nature  of  the  "flux,"  and  the  manner  of  its  incor- 
poration determines  the  fusibility  of  the  former  refractory  ingredients, 
and  the  tensile  strength,  or  resistance  :o  fracture,  of  the  mass  when  all 
are  fused  together. 

The  coloring  matter  employed  for  the  purpose 

Colorins  matter.       of  imparting  the  required  variations  of  shade  must 

necessarily  be  more  or  less  high  fusing  in  character, 

in  order  that  the  color,  or  tint,  may  not  be  dissipated,  or  burned  out,  in 

the  fusion  of  the  compound. 

While  the  coloring  matter  itself  has  practically  no  influence  upon  the 
fusibility  of  the  compound,  the  color  imparted  is,  however,  materially 
affected  by  the  degree  of  heat  required.  For  this  reason,  metals,  or  me- 
tallic oxides,  are  used  for  this  purpose,  in  which  the  basal  shades  im- 
parted are,  approximately,  as  follows : 


249 

Yellow,  Titanium. 

Brown,  Iron. 

Blue,  Cobalt. 

Gray,  Platinum. 

Pink    (gum   enamel),  Silver   and   tin   in   combination   with   gold 

(purple  of  cassius). 
The  colors  and  tints  characteristic  of  the  different  "bodies"  are  pro- 
duced by  the  use  of  these  in  various  compounds,  of  equally  varying  pro- 
portions, but  the  exact  formula  and  methods  of  procedure  are  of  special 
interest  to  the  manufacturers  only,  and  are  usually  more  or  less  care- 
fully guarded  by  them. 

'*l)lgb"  and  ''Eow"  Tusing  "  Bodies." 

The  several  varieties  of  "body"  now  prepared  may  be  classified  into 
two  distinct  grades — the  so-called  "high"  and  "low"  fusing,  with  the  line 
of  common  distinction  between  them  being  based,  approximately,  upon 
the  fusing  point  of  pure  gold. 

An  intelligent  analysis  of  the  comparative  quali- 

Comparative  ties   and  advantages   of   the  two   classes   of   "body" 

JIdPantases.  demands  a  more  or  less  limited  familiarity  with  the 

composition    of    these    compounds,     and     with     the 

characteristics  of  their  respective  ingredients. 

Silica  being  the  most  refractory  and  infusible  substance,  it  might  be 
commonly  supposed  that  a  "body"  capable  of  being  fused  at  a  lower 
temperature  than  another  would  necessarily  contain  less  of  this  ingre- 
dient and  more  feldspar  and  kaolin  in  proportion. 

Such  an  assumption  would  be  correct  if  the  "flux"  played  a  less  con- 
spicuous part  in  the  reduction,  but  the  same  relative  formula  of  the  three 
basal  ingredients  may  be  used,  and  yet  the  fusing  point  of  the  resulting 
compound  be  regulated  by  the  proportion  of  "flux"  subsequently  added 
to  this  formula. 

But  as  a  "body"  must  possess  sufficient  inherent  strength,  integrity 
and  stability  to  offer  a  high  degree  of  resistance  to  fracture,  and  must 
possess  translucency,  and  absence  of  opaqueness,  an  adequate  proportion 
of  these  three  basal  ingredients  seems  essentially  necessary,  since  each 
has  its  place  and  purposes  in  the  compound,  as  previously  indicated. 

This  being  apparent,  if  the  fusing  point  is  then  regulated  or  con- 
trolled by  the  proportion  of  "flux,"  and  it  is  conceded  that  the  latter  does 
not  impart  to  the  compound  the  highest  degree  of  strength  possible,  in 
the  light  of  our  present  knowledge  it  seems  reasonable  to  deduce  that, 
when  a  sufficient  proportion  of  "flux"  to  reduce  the  fusing  point  of  these 
refractory  materials  below  a  certain  point  is  incorporated,  the  maximum 
degree  of  strength  possible  is  not  imparted  to,  nor  obtained  in,  the  product. 


250 

It,  therefore,  seems  evident  that  when  a  maximum  degree  of 
strength  is  to  be  obtained,  such  as  is  required  in  the  construction  of 
crowns,  or  bridges,  where  at  best  the  friable  material  is  to  assume  the 
full  stress  of  mastication,  by  direct  contact,  the  compound  which  will  best 
serve  the  purpose  must  be  one  possessing  the  integrity  and  stability  im- 
parted by  the  three  basal  ingredients  to  a  degree  not  entirely  destroyed 
by  the  incorporation  of  too  great  a  proportion  of  "flux." 

All    porcelain    compounds    shrink   in    fusing   in 
Shrinkage.  proportion   to   the   degree   of  their  fineness   of   tex- 

ture, and  the  quantity  and  nature  of  the  "flux"  used ; 
and  the  degree  of  shrinkage  adds  to  the  difficulties  incident  to  their  man- 
ipulation with  certainty,  accuracy  and  expediency. 

The  "high"  fusing  compounds  shrink  from  ten  to  fifteen  per  cent, 
while  the  "low"  fusing  range  from  the  latter  point  up  to  25  per  cent, 
and  some  of  the  glass  or  extremely  low  fusing  "bodies"  which  contain 
lead  in  large  proportions  even  greatly  exceed  this.  There  is  never  any 
indication  for  the  use  of  the  latter,  however,  because  of  their  minimum 
strength,  and  of  their  invariable  tendency  to  discolor  in  the  mouth,  which 
may  be  attributed  to  the  presence  of  the  lead. 

All  of  the  compounds  are  more  or  less  porous,  and  hence  trans- 
lucent, in  proportion  to  the  degree  of  fineness  to  which  they  are  pulver- 
ized before  fusing.  Hence,  as  the  lower  fusing  "bodies"  are  always  re- 
duced to  a  much  finer  texture  in  their  preparation,  they  possess  a  greater 
density  of  structure. 

This  increased  density,  however,  is  due  to  the  more  homogeneous 
coalescence  of  the  particles  as  a  result  of  the  more  thorough  admixture 
of  the  "flux,"  and  is  gained  at  the  expense  of  translucency  and  stability, 
since  the  "flux,"  beyond  a  certain  proportion,  does  not  add  integrity  to  the 
mass,  but,  on  the  contrary,  increases  the  shrinkage,  friability  and  tendency 
to  globulate  in  fusing. 

The  degree  of  shrinkage  is  a  very  objectionable  feature  in  this  work, 
where  so  large  a  quantity  of  body  is  used,  because  the  resistance  to  the 
contraction  which  takes  place  in  the  lower  fusing  "bodies,"  and  which 
resistance  is  ofifered  by  contact  with  facing  and  cap,  induces  a  tendency 
to  fracture  which  greatly  diminishes  the  strength. 

A  summary  of  the  apparent  disadvantages  to  be  found  in  the  "low" 
fusing  "bodies"  thus  consists  in  their  degree  of  contraction;  their  dimin- 
ished strength  and  translucency,  and  their  lack  of  stability  of  form  and 
color. 

These  features  also  make  their  manipulation  with  accuracy  and  cer- 
tainty more  difficult,  particularly  for  the  inexperienced,  because  of  the 
necessity   for  shutting  off  the  heat  at  the  precise  degree  at  which  the 


proper  fusing  point  is  reached,  in  order  to  avoid  a  dissipation  of  the 
color,  and  a  loss  of  the  desired  form,  as  a  result  of  their  great  tendency 
to  become  spherical  immediate!}'  following  the  definite  and  exact  point 
of  fusion. 

For  these  various  reasons,  the  use  of  the  *'low"  fusing,  or  so-called 
"enamel  bodies,"  or  those  which  contain  a  large  enough  proportion  of 
"flux"  to  reduce  their  fusing  point  below  that  of  pure  gold,  and  to  de- 
crease the  stability  of  form  and  color,  which  are  imparted  largely  by  the 
three  basal  ingredients,  cannot  be  considered  at  the  present  time,  as  be- 
ing conservatively  reliable  for  this  special  class  of  work. 

Furthermore,  a  series  of  comparative  tests  for  crushing  and  tensile 
strength  of  most  of  the  various  "bodies""  now  ])rej)ared.  as  conducted  by 
Dr.  J.  E.  Nyman,  seems  to  prove  conclusively  that  the  most  useful  and 
reliable  compounds  for  this  class  of  work  are  to  be  found  among  those 
which  fuse  between  2,100°  and  2,500°  Fahrenheit,  with  the  pyrometer 
gauged  bv  the  fusing-  point  of  pure  gold,  as  being  2.016°. 

The  following  table  gives  the  approximate  fus- 

Tll$in0  Points.         ing  points  of  most  of  the  various  bodies  now  in  com- 
mon use,  as  well  as  of  the  different  makes  of  teeth, 
as  compiled  by  Mr.  J.  F.  Hamm.ond,  and  Dr.  \\'.  A.  Capon,  in  the  Ham- 
mond Electric  Furnace : 


"Body."  Current. 

Jenkins"s 110  volts. 

Ash's   Low   Fusing no 

Ash's   High    Fusing no      " 

Moffitt's    Porcelain 120 

Brewster's  Enamel no 

Consolidated's  High  Fusing,  no 

Whiteley's   Porcelain no 

Brewster's  Found  Body.  ...  no 

Close's  Found   Body no 

"White's   Porcelain no 

Parker's  Body 120      " 

Ash  and  Sons'  Tooth  Body,  no 

Sibley's   Tooth   Body no      " 

Dental     Protective's     Tooth 

Body    no      " 

Justi's  Tooth  Body no  volts. 

S.    S.   White's  Tooth    Body,  no      " 
Johnson    and    Lund's  Tooth 

Body    120      " 

Luken's'  Tooth   Body 120      " 

Century  Tooth  Body 120      " 

•Consolidated  Mfg.  Co.'s  Tooth 

Body    120      " 


Rheostat. 

T 

ime. 

Tern.  Fahr. 

I  St    step. 

2    1 

inin. 

1,544 

1st      " 

2 

1,544 

4th     " 

2 

1,904 

2d        " 

2 

2,047 

4th     " 

2 

(( 

2,084 

5th     " 

2 

2,192 

5th     " 

2 

2,210 

5th     " 

2 

2,300 

5th     " 

2 

2,300 

5th     " 

2 

(1 

2,300 

5th     " 

2 

a 

2,586 

4th     " 

2 

a 

2,264 

4th     " 

2 

11 

2,408 

5th     " 

2 

'•- 

2,440 

5th  step. 

2 

mm. 

2,440 

6th     " 

2 

(( 

2,516 

5th     " 

2 

" 

2,586 

5th     " 

2 

u 

2,606 

5th     " 

2 

a 

2,624 

5th 


2,624 


-2^2 


**6um  enamel"  *'Boaie$/' 

The  compounds  designated  as  "gum  enamel"  bodies  contain  a  larger 
proportion  of  "flux"  than  basal  bodies,  and  consequently  fuse  at  a  lower 
degree  of  heat,  and  possess  less  strength.  Hence,  when  their  use  is  in- 
dicated for  the  purpose  of  producing  an  artificial  restoration  of  the  gum 
color,  the  major  portion  of  the  contour  of  the  piece  should  be  made  of 
the  basal  "body,"  and  the  "gum  enamel"  subsequently  applied  where 
necessary,  and  only  for  the  purpose  of  imparting  the  gum  color. 

Previous  to  the  application  of  the  "gum  enamel,"  the  basal  "body" 
to  be  covered  by  it  should  be  fused  until  it  presents  a  fairly  smooth-  and 
well-vitrified  surface.  This  is  necessary,  because  it  is  not  to  be  re-fused, 
and  the  maximum  degree  of  strength  will  not  obtain  until  its  particles 
are  well  coalesced,  and  all  shrinkage  has  taken  place,  and  if  this  is  ac- 
complished at  the  time  of  the  fusion  of  the  "gum  enamel,"  the  color  of 
the  latter  will  likely  be  burned  out  or  dissipated,  owing  to  its  greater 
fusibility,  and  its  surface  will  present  innumerable  fractures,  as  a  result 
of  the  further  shrinkage  of  the  base. 

A  new  form  of  "gum  enamel"  has  been  introduced  by  Mr.  Robert 
Brewster,  of  Chicago.  This  consists  of  a  finely  pulverized  "body,"  which 
is  mixed  to  the  desired  consistency  with  oil,  and  then  painted  upon  the 
surface  and  fused,  in  the  manner  previously  indicated,  in  connection  with 
the  use  of  "oil  colors." 

It  would  seem  that  this  should  prove  to  be  the  ideal  method,  because 
the  same  effect,  and  greater  variations  in  shading,  may  be  obtained,  with- 
out diminishing  the  strength  or  increasing  the  weight  or  bulk  of  the 
finished  piece. 

Hcquirements  for  Crown  and  BriddeworR. 

A  class  of  "body"  possessing  qualities  adaptable  to  the  maximum  re- 
quirements for  crown  and  bridgework  will  thus  doubtless  belong  to  the 
high  fusing  variety,  and  should  be  prepared  in  one  grade;  of  a  sufficient 
variety  of  colors,  and  pulverized  only  to  a  degree  of  fineness  which  will 
admit  of  being  nicely  carved.  This  latter  feature  is  essential,  because 
the  shrinkage  is  increased  and  the  fusing  point  decreased  in  any  given 
compound  in  proportion  to  the  degree  of  fineness  in  which  it  is  prepared. 

Those  which  are  to  be  especially  recommended  are  Brewster's 
''Crown  and  Bridge;"  "S.  S.  White's;"  the  Consolidated  Dental  Mfg. 
Co.'s  and  Whiteley's  products,  all  of  which  are  supplied  in  neat  and 
compact  form,  in  a  good  variety  of  colors,  quite  adequate  to  the  require- 
ments for  this  work.  While  good  results  may  also  be  obtained  from  the 
use  of  Brewster's  "Inlay  Bodies,"  which  consist  of  tzvo  grades — "foun- 


253 

elation"  and  "enamel" — the  best  possible  results  arc  doubtless  facilitated 
and  afforded  by  the  employment  of  ojie  grade  of  material  throughout  the 
construction  of  the  piece,  and  no  difficulty  will  be  encountered  in  obtain- 
ing the  deisred  enamel  surface  in  any  of  these  compounds,  if  they  are 
fused  to  the  proper  degree  of  vitrification,  without  the  use  of  any  of  the 
lower  fusing,  or  so-called  "enamel  bodies"  in  conjunction  therewith. 

manipulation  of  ''Body/' 

That  portion  of  the  procedure  which  involves  the  manipulation  of 
the  "body"  requires  the  most  consummate  judgment  and  skill,  and,  while 
it  is  largely  true  that  the  strength  of  the  finished  piece  is  much  dependent 
upon  the  metal  constriiction  which  forms  the  foundation  for  the  porce- 
lain, the  degree  of  possible  strength  may  be  still  further  increased  by  skil- 
ful manipulation  of  the  latter,  or,  as  the  converse  is  equally  true,  it  may 
be  diminished  accordingly. 

When  the  crown  has  been  taken  from  the 
PreiHiration  Of  €rown.  investment,  after  soldering,  it  should  first  be  thor- 
oughly cleaned  in  50  per  cent  sulphuric  acid,  in  or- 
der to  insure  the  removal  of  all  remaining  traces  of  borax  or  investment 
material  which  may  cling  to  it,  and  which  would  be  apt  to  interfere  with 
the  subsequent  fusion  of  the  porcelain ;  and  the  presence  of  borax  is  par- 
ticularly objectionable,  because  it  acts  as  a  "flux." 

The  surplus  ends  of  the  dowel  and  pins  should  be  ground  down 
smooth,  and  so  that  they  offer  no  obstruction  to  the  contour,  and  afiford 
no  weakening  of  the  porcelain,  by  extending  or  projecting  into  it,  thus 
dividing  it  through  the  center,  and  all  sharp  angles  should  be  nicely 
rounded. 

These  requirements  are  imperative,  as  the  "body"  should  occupy  all 
of  the  space  possible.  It  will  not  fuse  down  close  nor  become  attached  to 
unclean  or  irregular  surfaces,  and  in  fusing  will  usually  either  draw  away 
from,  or  fracture  over,  sharp  angles  as  a  result  of  the  shrinkage. 

When  these  precautions  have  been  observed,  the  crown  should  be 
again  treated  to  the  acid  ba:th,  and  then  washed  freely  with  clean  water ; 
if  a  carborundnui  stone  has  been  used,  care  should  be  exercised  to 
remove  all  particles  which  may  cling  to,  or  remain  upon,  the  metal,  or 
facing,  as  the  presence  of  such  particles  will  invariably  cause  a  discolo- 
ration of  the  porcelain. 

A  close  observation  of  these  prerequisites,  combined  with  scrupulous 
care  and  extreme  cleanliness  throughout  the  subsequent  procedure,  will 
materially  increase  the  chances  of  securing  successful  results. 

These  results  will  also  be  greatly  facilitated  by  confining  the  work 


254 

to  a  place  especially  prepared  for  such  purposes,  or  to  a  portion  of  the 
work-bench  which  has  been  previously  cleaned  and  arranged ;  all  of 
the  necessary  instruments  and  appurtenances  to  be  used  should  likewise 
be  kept  perfectly  clean. 

When  a  suitable  place  to  work  is  thus  prepared, 
SekCtiOlt  9t  £olor.      and  the  crown  is  ready  for  the  application    of    the 
"body,"  its  dowel  should  be  grasped  firmly  between 
the  jaws  of  a  slide  pin-vise,  which  will  hold  it  securely  during  the  build- 
ing and  carving  (Fig.  197),  and  the  proper  color  of  "body"  then  selected. 

This  should  approach  the  shade  of  the  facing  when  one  is  used,  or 
else  of  the  color  desired,  as  closely  as  possible,  and  may  be  accomplished 
with  the  use  of  the  shade-guide,  which  accompanies  the  various  makes 
of  porcelain. 

If  the  exact  color  cannot  be  matched,  and  some  variation  becomes 
necessary,  a  shade  slightly  darker  than  the  facing  should  be  selected, 
owing  to  the  tendency  to  bleach  somewhat  in  fusing.  In  this  connection, 
it  must  be  remembered  that  the  true  color  of  the  porcelain  compound  will 
be  obtained  only  when  it  is  fused  to  the  exact  point  of  complete  vitrifica- 


FicjJ97. 

tion,  and  that  it  will  become  lighter  in  shade  as  it  is  carried  beyond,  or 
above,  this  point. 

An  adequate  quantity  of  the  "body,"  which  cor- 
mixing  "Body."  responds  in  color  to  that  selected  on  the  shade-guide, 
should  now  be  placed  upon  a  clean  porcelain  or  glass 
mixing  slab,  distilled  ivatcr  added,  and  then  mixed  thoroughly  with  a 
suitable  spatula,  until  it  assumes  the  consistency  of  thick  cream.  The 
water  may  be  added  in  the  most  convenient  and  expeditious  manner,  by 
means  of  the  "dropper,"  or  "pipette  bottle,"  such  as  is  contained  in  many 
outfits  for  this  work  and  which  also  serve  to  keep  it  pure  and  clean  for 
subsequent  use. 

Sufficient  water  to  insure  the  desired  consistency  and  thorough  mix- 
ing are  quite  essential,  and  any  surplus  of  "body"  is  not  wasted,  be- 
cause it  may  be  replaced  in  its  proper  receptacle  and  used  at  an- 
other time. 

Alcohol  is  sometimes  recommended  and  used  because  of  expediting 
the  evaporation  of  the  moisture  from  the  compound,  and  thus  facilitating 


255 

the  carving  of  the  mass,  but  this  feature,  because  of  usually  being  too 
rapid,  is  more  often  an  objection  than  an  advantage. 

The  addition  of  a  small  proportion  of  gum  tragacanth  to  the  water  is 
also  recommended  as  furnishing  a  means  of  adding  to  the  cohesion  of  the 
mass  after  the  evaporation  of  the  moisture,  and  thus  facilitating  the  carv- 
ing and  contouring,  but  its  presence  is  objectionable,  because  it  seemingly 
acts  as  a  "flux"  in  the  fusion  of  the  porcelain,  and  is  unnecessary,  because 
the  manufacturers  usually  incorporate  a  small  proportion  of  starch  in  the 
compound  for  this  special  purpose. 

The  use  of  pure  clean  water  is  preferable.  It  should  be  distilled, 
however,  because  the  presence  of  lime  or  organic  matter  may  have  an  in- 
jurious effect  upon  the  fusion  of  the  porcelain. 

Jlpplyind  ana  Buiiaind. 

In  the  manipulation  of  these  compounds,  it  must  be  remembered  that 
their  tendency  to  shrink  in  fusing  plays  quite  an  important  part,  and  gov- 
erns the  method  of  procedure  to  a  large  extent. 

In  the  use  of  one  grade  of    body,    haviiig    the 
"One  erade"         same   fusing   point,   throughout   the   construction    of 
Of  "Bofly."  the  piece,  the  desired  shape  and  contour  for  the  fin- 

ished crown  should  obtain   for  the  first,  or  primary 


"bake,"  and  yet  it  is  seldom  possible  and  never  expedient  to  complete  it 
in  one  "hake,"  because  of  the  shrinkage. 

This  latter  feature  necessitates  tzvo,  and  sometimes  even  more, 
"bakes,"  though  the  procedure  is  somewhat  facilitated  by  forming  the  de- 
sired contour,  even  to  the  requirements  of  occlusion  for  the  primary 
"bake,"  and  the  second  or  iinal  application  of  "body"  should  then  be  made 
for  the  express  purpose  of  restoring  that  portion  of  the  original  form 
which  has  been  somewhat  changed  by  the  shrinkage  incident  to  the  pri- 
mary fusion  or  "bake." 

With  the  crown  grasped  firmly  in  the  pin-vise  (Fig.  197).  and  the 
body  mixed  to  the  proper  consistency,  a  small  quantity  should  be  picked 
up  with  the  point  of  a  suitable  instrument  and  first  forced  into  the  joint 
between  cap  and  facing. 

This  may  be  facilitated  by  gently  tapping  the  handle  of  the  pin-vise, 
or  by  drawing  a  coarsely  serrated  instrument  across  it,  and  the  procedure 
should  be  continued  until  the  "body"  is  thoroughly  packed  into  the  space. 


2s6 

A  suitable  instrument,  designed  by  the  author,  for  universal  use  in 
this  work,  and  combining  a  spatula  for  mixing,  a  serrated  shank  for 
packing,  and  a  pointed  blade  for  carving,  is  illustrated  in  Fig.   198. 

This  feature  of  packing  is  imperative  throughout  the  entire  building 
up  of  the  crown,  as  a  means  of  insuring  a  high  degree  of  integrity  in  the 
mass  when  fused,  and  of  overcoming  the  tendency  toward  porosity  in 
fusing,  by  insuring  a  close  and  coynpact  coalescence  of  the  particles. 

As  the  building-  up  progresses  and  each  additional  application  of 
body  is  thus  carried  to  place,  and  the  contour  formed,  the  procedure  may 
be  facilitated  by  absorbing  the  excess  moisture,  as  it  is  brought  to  the 
surface,  with  a  clean  piece  of  linen  or  cotton  cloth,  or  blotting  or  bibulous 
paper,  until  the  approximate  outline  for  the  finished  crown,  zvith  a  slight 
surplus,  obtains. 

The  latter  part  of  the  procedure  may  be  accomplished  with  greater 
ease  and  facility  by  mixing  the  body  to  a  thicker  consistency  after  the 
joints  and  all  small  interstices  are  well  filled. 

When  the  required  form  has  been  obtained,  the  remaining  moisture 
may  be  then  more  quickly  evaporated  by  passing  the  crozvn  over  a  ftarn^ 
until  the  mass  is  sufficiently  dry  to  admit  of  being  nicely  carved. 

The  "body"  should  always  remain  moist  enough,  however,  to  be 
carved  and  trimmed  without  flaking  or  crumbling,  and  in  the  event  of 
its  becoming  too  dry  to  admit  of  this,  it  may  be  again  slightly  moistened 
by  touching  it  with  a  wet  brush. 

In  building  up  bicuspids  and  molars,  after  first  filling  the  joint,  a 
narrow  strip  of  blotting  paper  may  be  conformed  to  the  outline  of 
the  lingual  portion  of  the  band,  and  when  held  in  place  will  serve  as  a 
matrix  to  hold  the  body  in  shape  which  thus  facilitates  the  procedure. 

Variations  of  shade  may  be  quite  easily  obtained 
Uariations  In  Shading,  by  selecting  the  appropriate  colors  of  body  and  mix- 
ing them  separately.  The  color  indicated  for  the 
base  of  the  crown  should  then  be  applied,  and  built  up  to  the  desired 
point,  when  the  other  may  be  added  without  allowing  the  first  to  become 
completely  dry. 

Their  use  in  this  manner  afifords  opportunity  for  blending  them  in 
fusing,  and  very  artistic  results  are  possible,  particularly  in  those  cases 
where  the  base  should  be  yellow,  or  brown,  and  the  incisal  or  occlusal 
end  blue,  or  gray,  in  any  of  their  variations. 

The  use  of  the  oil  colors  previously  mentioned 
U$(  Of  on  Colors,       may   also   be  productive   of  most  excellent  and   ar- 
tistic results.     They  should  be  thoroughly  mixed  to 
a  thin   consistency,  with  the   accompanying  oil,   applied    with    a    small 
brush,  and  separately  fused. 


257 

Where  it  is  desirable  to  produce  a  change  in  the  color  of  the  facing, 
these  colors  should  be  applied  at  the  desired  point  on  the  lingual  surface, 
and  then  fused,  after  which  the  "Ijody"  may  be  applied,  as  required,  and 
the  underlying  color  will  show  through  the  more  or  less  transparent 
facing. 

An  appreciable  change  in  the  color  of  the  porcelain  forming  the  body 
of  the  crown  may  also  be  produced  by  applying  and  fusing  these  colors 
to  the  surface  after  the  primary  bake,  when  the  final  contouring  may  be 
■made,  the  transparency  of  which,  after  fusion,  will  indicate  the  presence 
•of  the  underlying  color. 

In  simulating  the  characteristics  of  remaining  natural  teeth,  grooves, 
J>its  and  sulci  may  be  colored  or  tinted  as  desired.  As  these  colors  fuse 
lower  than  the  "body,"  however,  this  work  can  be  done  to  the  best  ad- 
vantage after  the  croii'ii  has  been  otherzvise  completed ;  and  when  they 
are  used  for  such  purposes  on  the  labial  or  buccal  surfaces  of  the  facings, 
the  desired  inequalities  should  first  be  ground  with  a  small  carborundum 
stone  in  the  engine,  and  this  outline  then  properly  colored  or  tinted,  and 
the  crown  again  fused  until  the  colors  become  vitreous. 

If  not   too  dry,   the  procedure  incident  to  con- 
ContOUring  touring  and  carving  the  "body"  is  quite  simple,  but 

and  Carving.  the  artistic  results  will  depend  much  upon  personal 

equation  and  knowledge  of  the  forms  of  teeth. 

This  may  be  easily  acquired  by  a  close  study  of  natural  teeth,  and 
a  good  plaster  model  of  a  full  typical  arch  will  assist  by  serving  as  a  guide 
in  the  execution  of  this  work. 

As  has  been  previously  stated,  anatomically  correct  outlines  are  not 
•essentially  necessary,  and  artistic  results  may  be  obtained  bv  simplv  so 
typifying  the  cusps  as  to  distinguish  between  the  right  and  the  left,  the 
upper  and  the  lower  teeth. 

The  requirements  of  occlusion  with  the  opposing,  and  contact  with 
the  adjacent,  teeth  may  be  observed  by  trying  the  crown  upon  the  model 
during  the  process  of  carving,  and  in  order  to  prevent  flaking  the  body 
■or  changing  its  given  form,  it  may  be  carefully  and  slightly  moistened 
w^ith  a  wet  brush  previous  to  such  trials. 

For  this  reason,  it  is  always  necessary  to  have  a  good  model  to 
vi^hich  the  crown  may  be  easily  adjusted  to  position,  as  has  been  pre- 
^^iously  recommended. 

In  contouring  and  trimming  the  porcelain,  it  must  not  overlap  the 
band,  upon  any  surface,  nor  at  any  point,  excepting  along  the  labial  or 
buccal  surface,  tvhere  the  facing  mechanically  retains  it,  for  without 
such  means  of  retention  it  will  invariably  fracture  or  break  away,  leaving 
a  rough,  sharp,  or  irregular  joint  with  the  cap;  and  previous  to  placing 


258       • 

the  crown  in  the  furnace  all  particles  of  body  which  remain  deposited 
upon,  or  overlapping,  the  surface  of  the  facing,  or  which  may  have  found 
lodgment  on  the  inside  of  the  cap,  or  on  the  under  surface  of  the  base, 
should  be  carefully  removed  with  a  clean,  dry  brush  to  prevent  it  from 
becoming  attached  in  fusing. 

The  brushes  used  in  this  work  should  be  of  a  good  quality,  such  as 
are  employed  in  water  color  painting,  and  the  three  useful  sizes  and 
shapes  are  illustrated  in  Fig.  199.  The  largest  size  should  always  be 
kept  dry  and  used  only  for  smoothing  up  the  work,  while  the  medium 


FicfJQO 


Fiq.200. 


size  should  be  employed  for  the  purpose  of  moistening  the  "body,"  when 
necessary,  and  the  smaller  one  only  for  painting,  or  deepening  the  finer 
lines  in  carving. 

A  very  convenient  form  of  simple  carving  instrument,  designed  by 
Mr.  Robert  Brewster,  is  illustrated  in  Fig.  200. 

In  trimming  the  body,  the  allowance  of  a  slight  surplus  is  demanded 
by  the  shrinkage,  but  the  exact  extent  may  only  be  ascertained  with  ac- 
curacy by  a  familiarity  with  the  compound  used,  as  all  vary  considerably 
in  such  properties. 


259 

The  crown,  when  the  body  has  been  trimmed,  and  carved,  and  when 
ready  for  the  primary  "bake,"  is  illustrated  in  Fig.  201  A. 

When  this  desired  form,  and  blending  of  color. 

Primary  "Bake."      have  been  obtained,  the  crown  should  be  placed  in 

the  furnace  and   "baked"  until    the    body    becomes 

slightly  vitrified,  and  the  particles  well  coalesced,  Imt  its  surface  should 

not  be  highly  glazed  at  this  time. 

This  degree  of  fusion,  or  vitrification,  is  preferable  to  the  so-called 
biscuit  bake,  commonly  advocated,  because  of  the  desirability  of  securing 
a  maximum  degree  of  shrinkage  in  the  primary  fusion,  but  the  surface 
should  not  be  allowed  to  become  smooth  and  vitreous  at  this  time,  be- 
cause the  second  application  of  the  body  will  not  adhere  so  well  to  it. 
Fig.  201  B  illustrates  the  appearance  of  the  crown  after  the  "primary 
bake,"  and  indicates  the  degree  of  shrinkage  and  consequent  change  of 
form  wliich  takes  place. 


Fiq.201. 


For  the  final  "bake,"  the  crown  should  be  again 
Tinal  "Bake."  adjusted  in  the  pin-vise  and  the  "body"  thoroughly 
mixed,  to  a  thin  consistency,  and  first  zvorked'  zuell 
doimi  into  every  crevice  and  Ussure  caused  by  the  shrinkage,  and  then  ap- 
plied over  the  surface  until  the  desired  contour  has  been  obtained,  when  it 
should  be  fused  to  the  required  degree  of  vitrification  for  the  finished 
work,  which  is  illustrated  in  Fig.  201  C. 

If  the  crown  comes  out  of  the  furnace  after  this  "bake"  presenting 
an  irregular  or  broken  surface  of  porcelain,  such  places  should  be  filled 
with  "body,"  and  again  fused,  though  if  the  proper  precautions  are  ob- 
served, this  will  seldom  be  necessary. 

When  two  grades  of  "body"  which  fuse  at  dif- 
"Tounflatlon"  and     ferent  temperatures,   such  as  the  so-called  "founda- 
"CliailiCl"  Bodies,     tion"  and  "enamel  bodies,"  are  used,  the  requirements 
are  somewhat  different  from  those  indicated  for  one- 
grade  of  body,  because,  if  the  desired  contour  of  the  crown  is  obtained 
in  the  primary  formation  and  fusion,  it  will  be  difficult  to  manipulate  the 
"enamel"  body  for  the  final  bake,  as  it  will  necessarily  need  to  be  applied 
so  thinly  over  the  surface  of  the  "foundation"  body  as  to  preclude  any 


26o 

carving,  and  increase  the  tendency  to  flake  off,  or  become  detached  in 
places,  before  fusing. 

Hence,  where  it  is  desirable  to  use  two  grades,  the  higher  fusing,  or 
"foundation,"  body  should  be  applied  first,  only  in  quantity  sufficient  to 
indicate  the  desired  form,  as  illustrated  in  Fig.  202  A. 

This  should  be  fused  and  the  lower  fusing,  or  "enamel,"  body  then 
applied,  trimmed  and  carved  as  desired  (Fig.  202  B),  and  then  fused. 


Ficj.202. 

The  increased  quantity  of  the  latter  body  and  its  greater  shrinkage 
demands  an  allowance  of  more  surplus  than  would  be  necessary  if  the 
same  higher  fusing  body  were  used  throughout. 

Prccduficns  Incident  to  fusing. 

No  portion  of  this  work  is  of  more  importance  than  the  "baking" 
or  fusing  of  the  body,  because  the  strength  of  the  porcelain,  and  its  true 
color,  no  matter  to  which  class  it  belongs,  are  entirely  dependent  upon  its 
being  properly  fused. 


Fi(j.203. 


When  the   crown   is   ready   for   the   furnace,   it 

Supporting  Crown      must  be  adjusted  to    a    suitable    form,    which    will 

inTurnacc.  accommodate  the  dowel,  support    the    base    of    the 

croivn  by  allowing  it  to  rest  firmly  and  evenly,  and 

which  will  sustain  it  in  a  perpendicular  position  while  in  the  furnace. 

Whilst  platinum  trays  were  first  used,  and  are  even  now  occasionally 
recommended,  for  this  purpose,  their  employment  is  objectionable  be- 
cause crowns  not  infrequently  become  attached  to  them  in  fusing,  and 


26 1 

in  the  subsequent  detachment  the  porcelain  may  1)e  checked,  or  the  shape 
of  the  band  altered. 

This  attachment  may  be  due  to  the  re-fusion  and  flowing"  of  a  surplus 
of  the  pure  gold,  when  such  is  used  in  soldering,  or  to  an  excess,  or  the 
over-fusing,  of  the  porcelain,  but  whatever  the  cause,  may  be  precluded 
by  the  use  of  supports  made  of  fire-clay  or  chalk,  of  suitable  form. 

The  proper  adjustment  of  a  crown  with  and  without  a  band,  to  the 
style  of  support  indicated  for  each,  is  illustrated  in  Fig.  203. 

Such  supports  may  be  made  by  moulding  a  good  grade  of  fire-clay 
to  the  desired  shape,  and  "baking"  it ;  or  may  be  procured  in  various 
designs  to  meet  the  equally  varying  requirements  of  practically  inde- 
structible material  from  many  of  the  manufacturers  of  furnaces  and 
"bodies." 

Useful  designs  for  this  purpose  are  supplied  by  Dr.  R.  C.  Brophv, 
of  Chicago  (Fig.  204),  or  may  be  made  by  trimming  down  a  piece  of 
ordinary  blackboard  chalk  to  meet  the  requirements  of  the  case. 


The  latter  is  composed  of  compounds  of  magnesium  and  calcium, 
which  are  practically  infusible,  and  being  very  inexpensive,  it  is  quite 
useful.  Such  supports  will  serve  the  purpose  nicely  for  individual  fus- 
ings  and  may  even  be  used  two  or  three  times  before  the  form  is  lost. 

In  placing  the  crown  in  the  furnace,  it  should 

Placing  Crown        be  observed  that  the  dowel  does  not  extend  entirely 

in  furnace.  through  the  perforation  for  its  accommodation  in  the 

support,   so  as  to  bring  its  end  in  contact  with  the 

floor  of  the  muffle ;  and  that  the  facing  does  not  touch  the  dome  or  sides 

of  the  latter,  as  such  contact  in  either  instance  will  invariably  result  in  a 

fracture  of  the  facing,  due  to  too  rapid  heating,  or  uneven  expansion. 

The  crown  should  be  held  in  a  perpendicular  position,  if  possible, 
in  order  to  prevent  any  change  of  form  which  might  be  induced 
by  the  influence  of  gravity,  when  the  mass  is  in  the  fused  state;  and  the 
body  should  always  present  toward  the  opening  or  door  of  the  muffle,  so 
that   it  may  be  closely  watched  while  fusing.     This  latter  feature  is  of 


262 

special  importance,  because  if  the  body  is  not  visible  to  the  eye,  portions 
of  it  may  flake  off  unnoticed  during  the  heating  of  the  case,  and  neces- 
sitate a  subsequent  bake,  to  avoid  which  it  should  always  be  heated  care- 
fully and   watched    closely   during  the   fusing. 

As  a  matter  of  expediency,  the  heating  of  the 
1)Catin9  Turnace.       furnace  should  begin  immediately  preceding,  or  dur- 
ing, the  building  up  of  the  crown,  so  that  the  muffle 
will  be  thoroughly,  but  not  excessively,  heated  when  the  crown  is  ready 
for  the  baking. 

When  these  precautions  have  been  observed,  the  support  carrying 
the  crown  should  be  placed  near  the  opening  of  the  heated  muffle  and 
allowed  to  remain  for  a  few  moments,  in  order  to  become  thoroughly 
dry  before  it  is  placed  inside  of  the  furnace.  This  will  preclude  blistering 
the  surface  of  the  "body,"  or  the  displacement,  or  flaking,  of  particles 
from  the  crown,  as  a  result  of  the  expansion  of  the  remaining  moisture, 
which  would  be  induced  by  too  rapid  heating. 

In  placing  the  crown  in  the  furnace,  it  should  be  carried  to  a  posi- 
tion as  nearly  in  the  center  of  the  muffle  as  possible,  or  to  that  point  where 
there  are  the  greatest  number  of  heat  units.  For  the  reason  that  this  heat 
area  varies  to  a  considerable  extent,  it  is  seldom  advisable  in  the  smaller 
crown  furnaces,  with  the  opening  in  one  end  only,  to  fuse  more  than  one 
or  two  crowns  at  a  time,  and  if  each  is  to  be  baked  uniformly,  they  must 
be  placed  crosszvise  in  the  muffle,  in  order  to  get  such  a  result,  as  the 
temperature  decreases   toward  the  door  or  opening. 

Tuslitg. 

In  the  fusing  of  porcelain  "bodies"  the  physical  process  involved 
constitutes-  changing  the  powdered  granular  mass  into  a  vitreous  sub- 
stance, which  is  then  more  or  less  homogeneous  in  proportion  to  the 
thorough  admixture  of  the  "flux,"  or  the  degree  of  complete  coalescence 
of  all  of  the  particles. 

Hence  the  proper  fusing  of  these  compounds  is  largely  a  matter  of 
experience.  In  the  lower  fusing  "bodies"  the  proper  and  desired  degree 
of  vitrification  may  be  easily  and  definitely  ascertained  by  observing  this 
physical  change  as  it  is  produced  by  the  application  of  heat.  This  is  also 
true  of  the  higher  fusing  bodies,  but  the  greater  degree  of  heat  required, 
and  the  consequent  incandescence  within  the  furnace  makes  it  more  diffi- 
cult. The  eye  may  be  trained  to  a  degree  of  familiarity  with  the  physical 
changes,  however,  which  will  enable  the  experienced  operator  to  more 
or  less  easily  distinguish  the  disappearance  of  the  rough  or  granular  sur- 
face, and  the  appearance  of  the  smooth,  glassy  or  vitreous  surface  even 
in  the,  at  first,  somewhat  trying  glare  of  the  incandescent  heat,  v/ithout 


263 

greatly  endangering-  or  impairing  the  sight,  because  it  is  not  necessary 
to  bring  the  eyes  close  enour^h  to  the  furnace  to  be  seriously  affected  by 
the  heat. 

Smoked  or  colored  glasses  may  be  found  useful  in  this  connection, 
and  during  the  fusing  of  the  "body"  the  furnace  may  be  occasionally 
opened  for  this  purpose  without  danger  of  fracturing  the  facing,  be- 
cause the  volume  of  heat  is  too  great  to  admit  of  the  ingress  of  cold  air. 

\\niile  everyone  desiring  to  do  this  class  of  work  in  the  most  accurate 
and  successful  manner  should  cultivate  this  degree  of  familiarity  with  the 
characteristic  appearance  of  the  "body"  in  the  various  stages  of  vitrifica- 
tion, it  can  only  be  acquired  through  experience.  When  the  crown  is 
properly  placed  in  the  furnace  the  heat  should  Ije  gradually  increased 
imtil  a  bright  red  color  is  produced.  This  may  be  done  bv  degrees  with- 
out observing  the  crown  itself,  but  from  this  point  on  the  latter  should  be 
watched  closely  so  as  to  observe  when  the  rough  and  granular  surface 
becomes  smooth  and  vitreous,  which  to  the  experienced  eye  is  indicated 
by  the  degree  of  incandescence,  and  as  soon  as  a  glassy  appearance  has 
spread  over  the  entire  surface  of  the  porcelain  the  heat  should  be  imme- 
diately turned  off. 

Many   tests   for  determining  the  exact  heat  re- 
te$t$.  quired   to   properly   fuse  the  various   "bodies"   have 

been  suggested.  Alloys  of  platinum  and  gold  pre- 
pared in  various  proportions  with  a  view  to  having  the  test  metal  melt  at 
the  same  point  as  the  porcelain  would  greatly  facilitate  the  fusing,  but  as 
this  requires  a  special  alloy  for  each  kind  of  "body,"  and  as  these  are  not 
on  sale  ready  prepared  at  the  present  time,  it  involves  considerable  experi- 
mentation to  apply  this  method. 

Pure   gold   may   be   used   with   some   degree  of 
Pure  Gold.  facility,  and  its   use   is  recommended  as  a  guide  to 

the  beginner  and  an  aid  even  to  the  experienced.  A 
pellet  of  foil,  or  a  globule  previously  flattened  on  the  anvil  for  each  fus- 
ing may  be  placed  alongside  of  the  crown  in  the  furnace.  When  this 
fuses,  which  may  be  noted  by  its  assu-iing  globular  form,  the  beginning 
of  vitrification  of  nearly  all  of  the  higher  fusing  bodies  will  be  indicated. 

From  the  moment  of  the  fusion  of  the  gold  to  the  required  or  de- 
sired point  of  vitrification  of  the  porcelain,  time  is  the  only  reliable  test 
other  than  the  eye,  and  as  this  varies  with  each  furnace  and  class  of  bodv, 
it  must  be  previously  more  or  less  definitely  ascertained  by  experimen- 
tation. 

The  separate  fusing  of  several  cubes  of  the  "body"  used  will  enable 
one  to  ascertain  the  exact  time  after  the  fusion  of  the  pure  gold  with 
approximate  exactness.     \\'hen  the  desired    ooint    of    fusion    has    been 


264 

reached  the  heat  should  be  immediately  shut  off,  and  the  crown  allowed 
to  cool  slowly  until  a  low  temperature  obtains,  when  it  may  be  removed 
from  the  furnace.  Whilst  immediate  removal  as  soon  as  the  heat  is 
turned  off,  and  then  placing  the  crown  in  a  cooling  muffle,  or  in  some  con- 
venient receptacle  where  the  air  will  be  excluded  until  it  is  cold,  is  some- 
times recommended,  and  is  permissible  in  emergencies,  the  furnace  itself 
affords  the  best  "cooling  muffle,"  and  the  slow  and  gradual  cooling  of 
the  piece  seems  to  ^'temper'  or  anneal  the  body,^  and  thus  render  it  less 
brittle. 

Porosity  of  the  body  after  fusing  is  one  of  the 
Pcro<ity.  chief  causes  of  failure  in  this  work.     When  this  oc- 

curs it  may  invariably  be  attributed  to  one  of  three 
causes,- — the  use  of  a  surplus  of  pure  gold  in  soldering;  imperfectly 
"packing"  the  body  in  building  up  the  crown,  or  overfusing  it  in  the 
furnace. 


FI<].205. 


An  excess  of  pure  gold  which  occupies  space  and  which  space  sub- 
sequently becomes  a  vacuum  when  the  gold  is  fused  in  the  furnace  and 
absorbed  by  the  platinum,  can  be  avoided  by  using  a  minimum  quantity 
of,  and  properly  fusing  the  gold  during  the  process  of  soldering. 

There  is  no  excuse  for  imperfect  "packing"  if  the  precautions  indi- 
cated are  observed ;  and  "overfusing,"  which  will  be  denoted  by  the  be- 
ginning of  a  change  of  form,  will  not  occur  if  the  case  is  watched  closely 
while  in  the  furnace,  or  the  time  test  is  accurate.  This  is  extremely 
essential  to  the  success  of  the  finished  work,  because  overfusing  burns 
out,  or  dissipates,  the  color,  and  destroys  the  integrity  of  the  material,  no 
matter  to  which  class  it  belongs. 

When  the  final  baking  has  been  completed  the  exposed  lingual  sur— 


265 

face  and  entire  edge  of  the  i)latinum  band  should  Ije  smoothed  with  sand- 
paper and  polished  with  cuttle-fish  disks,  and  the  crown  then  tried  to 
place  and  mounted. 

Turnaces. 

Several  varieties  of  furnaces  arc  now  made  for  porcelain  work  in 
which  three  sources  of  heat  production  are  successfully  employed, — elec- 
tricity, gasoline  and  gas. 

The  electric  furnaces,  or  "ovens,"  in  which  the 

Electric  Turnaccs.      heat    is    obtained    by    the    passing    of    the    current 

through    a    close    coiling    of    small    platinum    wire 

slightly  imbedded  in  fire-clay  without  contact,  or  wound  around  the  (jut- 


Fici.206. 

side  of  a  thin  muffle,  possess  the  advantages  of  purity,  range  and  control 
of  heat,  and  of  cleanliness  and  the  absence  of  noise  or  odor. 

Owing  to  the  absolute  purity  of  the  heat  thus  obtained  any  possible 
danger  of  discoloring  the  porcelain  from  "gassing,"  is  eliminated;  and 
for  all  of  the  combined  reasons  mentioned  the  use  of  the  electric  furnace 
is  recommended  wherever  it  is  possible  to  secure  suitable  commercial 
current,  such  as  is  supplied  for  incandescent  purposes. 

Of  the  several  makes  of  these  furnaces  especially  constructed  for 
small  work,  such  as  single  crowns  and  small  bridges,  those  designed  by 


266 

Mr.  J.  F.  Hammond,  of  New  York,  and  Dr.  L.  E.  Custer,  of  Dayton, 
Ohio,  are  to  be  especially  recommended  as  being  neat,  compact  and  serv- 
iceable, as  are  also  the  "Hewett'"  and  "Pelton"  designs. 

These  furnaces  include  a  rheostat  in  serial  connection  with  the  muffle 
or  "oven"  and  forming  the  base  of  the  furnace,  and  they  work  equally 
well  on  either  the  direct  or  alternating  currents  of  the  same  voltage. 

While  the  two  former  furnaces  are  made  in  three  sizes,  the  Hammond 
No.  2,  Fig.  205,  and  the  Custer  No.  5,  Fig.  206,  will  be  found  to  be  the 
most  convenient  size  for  this  special  work,  though  there  is  no  objection  to 
using  the  larger  sizes  which  are  designed  for  continuous  gum  work  when 
several  crowns  at  one  time,  or  large  bridges,  are  to  be  "baked." 

As  the  larger  sizes  require  more  time  in  fusing,  it  is  more  expedient 
to  use  the  smaller  ones  for  crown  work.  The  opening  in  the  latter, 
however,  is  in  one  end,  hence  the  heat  is  greatest  as  the  back  wall  of  the 
muffle  is  approached.  For  this  reason,  if  more  than  one  piece  is  "baked" 
at  the  same  time,  they  must  be  placed  crosswise  and  not  lengthzvise  with 
the  muffle,   in  order  that  the  porcelain  may  be  uniformly  fused. 


F/Q.P07. 


When  the  piece  is  adjusted  in  the  heated  furnace  it  should  be 
allowed  to  remain  for  a  few  moments,  and  the  lever  controlling  the 
rheostat  then  gradually  and  consecutively  pushed  from  button  to  button, 
with  an  interval  of  from  one  to  two  minutes  between  each.  When  the 
last  or  highest  step  required  is  reached,  the  case  should  be  closely  watched 
until  the  body  is  properly  fused,  or  timed  from  the  fusing  of  the  pure 
gold,  when  the  lever  should  be  immediately  reversed,  and  the  piece 
allowed  to  cool  more  or  less  slowly  before  removing. 

Convenient  pliers  of  special  design,  suitable  for  inserting  or  remov- 
ing the  support  containing  the  piece,  are  illustrated  in  Fig.  207,  but, 
while  these  are  also  very  useful  for  solder  work  in  general,  because  of 
their  length,  a  special  pair,  kept  perfectly  clean,  should  be  used  for  this 
work.  In  using  pliers  in  the  furnace,  however,  when  the  current  is  turned 
on  care  must  be  exercised  to  avoid  bringing  them  in  contact  with  the 
wires,  and  thus  possibly  fusing  the  latter  or  "burning  out"  the  furnace 
by  short-circuiting.  ^    •- 


26/ 


Ficj,20Q. 


Ficj.  209. 


268 

Where  it   is  not  possible   to  secure  commercial 
6il$0UMC  TUI'nact$.     electric    current,    and    for    reasons  of  possible  emer- 
gency and  economy,  the  gasoline  and  gas  furnaces, 
as  now  made,  will  serve  the  purpose  nicely,  and  when  properly  used,  will 
furnish  adequate  heat. 

While  it  is  true  that  such  facilities  do  not  afford  the  same  degree 
of  absolute  purity  of  heat,  there  is  but  little  danger  of  "gassing"  or  dis- 
coloring the  porcelain,  in  their  use,  if  the  continuity  of  the  muffle  is  per- 
fect. 

The  gasoline  furnace  is  preferable  to  gas  because  the  heat  produc- 
tion is  aided  by  means  of  a  pneumatic  pump  and  the  one  manufactured 
by  Dr.  R.  C.  Brophy,  of  Chicago,  Fig.  208,  especially  designed  for  crown 


5-^.210. 


and  bridgework,  is  adequate  to  the  requirements  in  every  respect.  This 
furnace  is  made  in  two  styles,  one  with  a  very  thin  fire-clay  muffle,  and 
the  other  with  a  nickel  muffle,  both  of  which  are  quite  serviceable,  with 
the  preference  perhaps  slightly  in  favor  of  the  former. 

The  Turner  gasoline  furnace,  Fig.  209,  manufactured  by  the  Turner 
Brass  Works,  of  Chicago,  is  similar  in  design  (except  that  the  nickel 
muffle  is  exclusively  used),  and  is  perhaps  equally  as  effective. 

In  the  use  of  these  furnaces  they  should  be  started  and  well  heated 
before  the  work  is  placed  in  the  muffle,  and  the  piece  should  first  be 
thoroughly  dried  and  heated  at  the  opening  before  being  carried  into  the 
inside. 

As  the  muffle  opens  from  one  end  the  same  precautions  indicated 
in  connection  with  rimilarlv  constructed  electric  furnaces  should  be  ob- 


269 

served,  and  when  the  work  is  finally  adjusted  to  place,  the  opening  should 
be  closed  as  a  means  of  confining  the  heat  to  the  inside  and  preserving 
its  purity. 

The  fusing  of  the  porcelain  may  be  known  either  by  watching  with 
the  eye,  or  by  gold  and  time  test,  as  previously  described,  in  which  the 
"plug"  closing  the  opening  of  the  muffle  may  be  frequently  removed  for 
the  purpose  of  observation,  and  the  same  requirements  incident  to  turn- 
ing off  the  heat,  and  allowing  the  work  to  cool  slowly  should  also  be 
observed. 

If  the  required  heat  is  to  be  obtained  with  facility,  the  supply  of  air 
must  not  be  allowed  to  become  diminished,  hence  the  pump  must  be  used 
with  sufficient  frequency  to  maintain  high  pressure. 

It  is  also  necessary  to  watch  the  condition  of  the  muffle  in  order  that 
it  may  be  replaced  when  the  continuity  becomes  destroyed  by  disintegra- 
tion, by  which  means  the  possibility  of  "gassing"  the  work  will  be  largely 
overcome ;  and,  the  greater  facility  with  which  this  may  be  done,  to- 
gether with  the  inclosed  shelf  at  the  opening  of  the  muffle,  for  heating 
the  work,  and  the  larger  size  of  the  latter,  constitute  the  main  advan- 
tages of  the  first-mentioned  furnace. 

The  gas  furnace  designed  by  Dr.  R.  C.  Brophy, 
6a$  Turnacw.  Fig.  210,  may  also  be  successfully  used.     As  a  sup- 

ply of  air  sufficient  to  afford  complete  combustion 
with  illuminating  gas  is  needed,  however,  the  employment  of  compressed 
air,  or  the  use  of  the  "bellows"  becomes  necessary,  and  in  the  absence 
of  the  former,  the  effort  required  is  of  course  much  greater  than  that  in 
the  use  of  gasoline.  Where  compressed  air  is  available,  this  furnace  is 
to  be  especially  recommended. 

The  more  or  less  objectionable  odor  which  emanates  from  the  use  of 
gasoline,  however,  is  overcome,  but  the  noise  produced  by  the  combus- 
tion in  each  is  one  of  the  most  unfavorable  features  in  connection  with 
the  use  of  either  of  these  furnaces. 


insertion  of  6oia  fillings  in  Jlrtificial  tcciD. 


CHAPTER  XIV. 

Indications.     Methods:  Foil  Gold,  "Roman"  Gold,   In   Combination  with  Backing; 

Procedure. 


The  insertion  of  gold  fillings  in  porcelain  facings  employed  in  the 
construction  of  crowns  and  bridges  is  very  often  indicated  as  a  means  of 
simulating  the  remaining  natural  teeth,  and  thus  observing,  and  complying 
with,  the  requirements  of  harmony,  and  with  a  view  to  and  for  the  purpose 
of  obtaining  increased  esthetic  and  artistic  results,  as  has  been  previously 
mentioned. 

In    the    construction    of    individual    crowns    for 
Tndications.  an}-  of  the  anterior  teeth,  if  the  remaining  adjacent 

natural  teeth  are  more  or  less  freely  filled  with  gold, 
the  crown  should  almost  invariably  carry  one,  and  sometimes  two,  small 
approximal  fillings ;  and  in  bridgework  involving  the  upper  anterior  teeth, 
where  the  lower  anterior  teeth  are  likewise  filled,  the  insertion  of  one  or 
two  small  fillings  in  appropriate  locations  will  often  aid  materially  in 
detracting  from  the  artificial,  and  adding  to  the  natural,  appearance  of 
the  work. 

Such  filling's  should  never  be  inserted,  however,  with  a  view  of  making 
the  work  conspicuous,  nor  for  the  exclusive  purpose  of  additional  remu- 
neration, and  should  be  no  larger  than  necessary  to  effect  the  harmony 
and  legitimate  deception  which  may  be  thus  indicated  by  the  adjacent 
natural  teeth. 

The  methods  employed  in  accomplishing  this 
methods.  work  consist  in  preparing  a  retentive  cavity  and  filling 

it  with  foil  gold ;  in  the  use  of  liquid  or  "Roman" 
gold,  which  is  painted  over  the  desired  area,  and  then  -fired  in  the  furnace, 
in  a  manner  similar  to  that  employed  in  china  decorating;  and  the  con- 
struction of  the  filling  as  a  part  of  the  backing. 


271 

In  the  employment  of  this  method,  which  is  per- 

Toil  Gold.  haps  the  most  generally  used,  and  which  affords  the 

most  permanent,   expeditious  and  artistic  results,  a 

cavity,  in  the  appropriate  location  and  of  the  desired  form,  should  he  first 

outlined  in  the  facing  with  a  small  fine  carborundum-stone.    (Fig.  211a.) 

This  outline  facilitates  the  cutting  or  drilling  of  a  cavity  of  the  neces- 
sary retentive  form  and  affords  a  definite  marginal  edgt  for  the  subsequent 
adaptation  and  finishing  of  the  gold. 

When  so  formed,  adequate  retention  may  then  be  secured  by  driUing 
a  simple  countersunk  cavity  of  sufificient  proportions  in  the  center  of  the 
outlined  area   (Fig.  211b),  or  by  cutting  retentive  grooves   (Fig.  211c). 

For  the  former  purpose,  which  is  more  generally  applicable  to  small 
cavities,  an  inexpensive  diamond  drill,  to  be  used  in  the  engine,  is  made 
by  the  S.  S.  White  Dental  Manufacturing  Com])any  (Fig.  212a).  while 
the  retaining  grooves,  which  are  best  adapted  to  larger  cavities,  may  be 
easily  cut  with  a  sm.all  copper  disk  coated  with  diamond  dust,  which  is 
also   prepared    for   this   and   similar  purposes    (Fig.   212b),  or  with   the 


"cavity  cutting"'  outfit  manufactured  by  the  same  company,  and  which 
consists  of  a  set  of  engine  instruments  of  oval  form,  and  graded  sizes, 
and  a  cutting  material  composed  of  carborundum  dust  and  glycerol. 

While  this  latter  method  accomplishes  the  \vork  nicely,  it  is  scarcely 
so  expeditious  as  the  two  former  procedures,  in  the  use  of  which  the 
rapidity  of  their  cutting  properties  is  facilitated,  and  the  danger  of 
fracturing  the  facing  is  entirely  eliminated,  by  the  free,  use  of  oil  or 
glycerine  as  a  lubricant.  This  saves  the  instrument,  and  prevents  the 
creation  of  heat  otherwise  induced  bv  friction,  which  might  cause  fracture. 

When  the  proper  retention  has  beer  secured,  the  cavity  should  be 
thorough!}'  cleaned  with  soap  and  water  and  dried  with  alcohol  and  hot 
air,  and  then  filled  with  small  pellets  of  gold  in  the  ordinary  manner,  and 
finished  as  usual   (Fig.  21  id). 

While  it  is  usnall}-  aflvrsable  to  defer  the  insertion  of  such  fillings 
until  after  the  campletron  of  the  work,  in  order  that  any  subsequent 
.scratching  or  defacing  of  the  surface  may  be  prevented,  it  may  frequently 


272 

become  necessary,  or  seem  desirable,  to  insert  them  before  the  construc- 
tion of  the  work,  or  the  assemblage  of  the  parts. 

This  may  be  essential  in  bridgework  constructed  with  gold  to  admit 
of  placing  the  cavity  in  the  desired  location  upon  the.  approximal  surface, 
and  when  here  or  otherwise  indicated  the  procedure  may  be  greatly  facili- 
tated by  imbedding  the  facing  in  a  base  of  modelling  compound  or  sealing 
wax,  as  a  means  of  holding.it  securely '(Fig.  213). 

In  porcelain  work,  however,  the  procedure  must  necessarily  be 
deferred  until  the  piece  has  been  finished,  in  order  to  preclude  fusing  the 
gold,  and  the  same  is  likewise  advisable  in  single  crowns,  for  the  reason 
mentioned,  and  in  any  event  the  preparation  of  cavity  and  insertion  of 
filling  should  be  don«  at  the  same  time. 


O 


a 


Fi<j.  213. 


Z/'^.  212. 


In  the  use  of  the  so-called  "Roman"  gold,  which 
Roman  Gold.  is  prepared  for  similar  decorative  purposes,  and  quite 

applicable  to  this,  the  cavity  area  should  be  first  out- 
lined, as  indicated  in  Fig.  211a,  and  the  gold  then  mixed  into  a  paste 
of  proper  consistency  and  painted  thickly  over  the  surface,  being  careful 
to  observe  that  it  closely  follows  and  evenly  approximates  the  cavity 
margins. 

The  facing  should  now  be  placed  near  a  flame,  or  close  to  the  previ- 
ously heated  furnace,  and  allowed  to  remain  until  the  gold  has  become 
thoroughly  dry,  when  it  should  be  placed  in  the  furnace  and  "fired"  until 
the  gold  fuses,  which  may  be  readily  observed  by  its  vitreous  appearance. 
After  allowing  to  cool  more  or  less  slowly,  the  filling  may  be  easily 
finished  and  polished  with  burnishers,  or  Unc  cuttle-fish  disks,  and  the 
bufif  wheel. 


273 

In  gold  work  such  fillings  should  be  made  before  the  final  attachment 
■of  the  facing  to  the  metal  parts,  with  solder,  while  in  porcelain  work  the 
lower  heat  required  to  fuse  the  gold  demands  that  they  be  made  after  the 
•completion  of  the  piece. 

While  this  method  affords  artistic  results,  the  objections  to  it  lie  in 
the  fact  that  such  fillings  are  likely  to  be  less  permanent,  because  of  a 
tendency  to  flake  and  chip. 

A    method   involving   a   less   simple    detail,   and 
Tn  Combination        requiring  more  time,  perhaps,  but  productive  of  very 

Witb  Bacliing.  artistic  results,  is  applicable  to  gold  work,  and  con- 

sists of  making  the  filling  in   combination   with  and 
:as  a  part  of  the  backing. 

Its  employment  is  indicated  more  especially,  however,  in  simulating 
.approximal  fillings  involving  the  incisal  angle,  which  is  sometimes  desir- 
able, and  which  would  be  more  or  less  difficult  by  the  other  methods, 


Ticcause  of.  the  limited  opportunity  aft'orded  by  the  ordinary  facing  for 
.-securing  adequate  anchorage  for  such  fillings. 

When  such  a  filling   is    indicated,    or    where    it 

Procedure.  may  be  desirable  to  employ  this  method,  the  facing 

should  be  first  ground  to  the  proper  and   required 

-adaptation,  and  then  prepared  for  the  reception  of  the  backing,  in  the 

nisual  manner. 

That  portion  of  the  porcelain  which  involves  the  location  and  area 
•of  the  desired  cavity  formation  and  gold  restoration  should  then  be  ground 
away  on  a  slight  bevel  tozuard  the  lingual  side,  tmtil  a  perfectly  smooth 
rmarginal  outline  has  been  secured   (Fig.  214a). 

A  backing  of  about  34  gauge  pure  gold  should  now  be  adapted  to 
the  facing,  and  burnished  up  well  against  the  cavity  margin,  allowing  a 
surplus  of  about  1/32  of  an  inch  to  project  beyond  the  latter,  and  upon 
the  incisal  end  (Fig.  214b).  When  this  has  been  accomplished,  a  piece 
of  22  karat  gold  plate,  29  or  30  gauge,  should  be  adapted  to  this,  extend- 
ing from  the  pins  to  the  incisal  end,  and  projecting  out  to  the  original 


outline  of  that  portion  of  the  facing  which  has  been  destroyed  (Fig. 
214c). 

This  forms  a  matrix,  indicating  the  desired  formation  of  the  iiUing, 
and  the  two  backings  should  now  be  removed  and  united  with  solder  in 
the  manner  previously  described  in  connection  with  "re-enforced  backings.'^ 
Their  detachment  from  the  facing  without  danger  of  changing  the  shape 
of  the  thinner  one  is  made  possible  and  facilitated  by  the  slight  lingual 
bevel  given  to  the  cavity  wall  in  its  preparation. 

When  their  union  has  been  eiTected,  the  matrix  formed  by  the  two 
backings  should  be  filled  with  22  or  20  karat  solder  until  the  desired 
contour  obtains   (Fig.  2i4d). 

This  should  then  be  adjusted  to  the  facing,  securely  attached  by 
bending  the  pins,  and  finished  with  files,  stones  and  disks  until  the  adapta- 
tion of  the  backing  and  the  contour  of  the  filling  are  as  desired  (Fig. 
2i4e).  when  the  piece  may  l^e  completed  and  finished  in  the  usual  manner. 

In  securing  the  desired  contour  of  the  filling  with  solder,  a  high 
karat  must,  of  course,  be  used,  because  of  the  susceptibility  to  discolora- 
tion, and  clean  flux  must  be  applied  to  avoid  a  pitted  surface. 

In  flowing  the  solder,  it  is  also  well  to  observe  the  precaution  of 
fitting  a  piece  of  gold  or  platinum  wire  or  plate  into  the  matrix  before  the 
procedure,  as  this  insures  a  preservation  of  the  adaptation  of  the  pure 
gold  to  the  cavity  margin,  which  otherwise  might  be  somewhat  changed 
bv  shrinkage,  if  solder  alone  be  used. 


finishing,  PolisDind  and  mounting. 


CHAPTER   XV. 

Finishing.  Polishing:  Facilitating  Procedure.  Precautions.  Gold  Plating.  Cyan- 
ide Solutions,  Prepared  Solutions.  Mounting:  Preliminary  Adjustment; 
Temporary  Mounting;  Permanent  Mounting;  Use  of  Cement;  Procedure; 
Dowel  Crowns,  Shell  or  Telescop-  Crowns,  Insuring  Accuracy  of  .Adapta- 
tion to  Root,  Two  or  iMorc  Crowns,  Therapeutics.  Use  of  Gutta  Perclia ; 
Advantages,  Disadvantages,  Procedure;  Dowel  Crowns,  Shell  or  Telescope 
Crowns,  Final  Mounting.  Combining  Cement  and  Gutta  Percha ;  Procedure. 
Variations  of  Procedure;  Use  of  Chloropercha ;  Use  of  Shellac  and  Sandarac; 
Rubber  Tissue.  Final  Precautions.  Removing  Crowns  Mounted  with  Gutta 
Percha. 


The  finishing-,  poHshing-  and  mounting  of  crowns,  while  ahnost 
equally  as  important  as  any  other  special  portions  of  the  work,  are,  never- 
theless, quite  often  neglected  or  done  in  a  more  or  less  perfunctory  man- 
ner, because  of  not  being  fully  appreciated. 

This  should  not  be  so  in  any  single  instance,  for  the  reason  that 
proper  finishing  and  polishing  adds  materially,  not  only  to  the  artistic 
appearance,  but  also,  and  particularly  where  gold  is  used,  to  the  increased 
hygienic  condition  presented  in  the  finished  piece;  and  successful  mount- 
ing has  much  to  do  with  the  degree  of  comfort  and  permanency  of  the 
operation. 

Tinishiitd. 

When  the  case  has  been  removed  from  the  investment,  it  should 
first  be  treated  to  the  acid  bath  for  a  sufficient  length  of  time  to  insure  the 
thorough  removal  of  all  products  of  oxidation,  and  of  all  particles  of 
investment  material  and  "fiux."  After  this  has  been  effectually  accom- 
plished, the  acid  should  be  thoroughly  removed  by  washing  freely  with 
clean  water,  and  the  case  then  finished  in  accordance  with  the  require- 
ments, and  with  the  maximum  of  artistic  possibilities  to  which  gold  and 
platinum  are  so  highly  susceptible,  as  is  evidenced  in  the  jeweler's  art, 
and  in  jeweler's  products. 

The  primary  efforts  in  finishing  should  consist  in  obtaining  the  re- 
quired contour;  the  desired  obliteration   of  all  joints,  and  evenness  and 


2/6 

smoothness  of  the  surfaces  ;  and  should  inckide  removing,  or  diminish- 
ing any  undesirable  or  unnecessary  display  of  metal  upon  any  surface. 
Owing  to  the  small  size  of  the  piece,  this  may  usually  be  best  accom- 
plished with  small  carborundum  stones,  of  coarse  and  medium  grit,  used 
in  the  engine.  These  should  be  followed  with  emery  or  sandpaper  disks 
of  medium  grit^  and  subsequently  with  very  fine,  or  cuttlefish,  disks, 
until  every  scratch  is  removed,  and  the  surfaces  are  perfectly  smooth. 

A  more  finished  and  artistic  appearance  may  be  given  to  the  lingual 
surfaces  of  anterior  crowns  with  gold  backings  by  making  an  effort  to 
reproduce  the  natural  shape  and  form  of  this  surface  in  the  gold  (Fig. 


FA 


^•215, 


F/cj.  216. 

215),   which  may  be  easily  and  quickly  done  with   a  knife-edge  carbo- 
rundum stone,  and  plug-finishing  burs. 


Polisbiiid. 

This  should  then  be  followed  by  highly  polishing  the  metal  with  felt 
and  brush  wheels  on  the  lathe.  The  primary  polishing  should  be  ob- 
tained with  a  thin-edge  felt  wheel  (Fig.  216)  and  moistened  pumice  stone 
of  medium  grit;  and  the  wheel  should  be  previously  soaked. in  water,  so 
that  it  will  absorb  and  carry  the  pumice  stone  with  it  during  the  proce- 
dure. 

When  the  desired  smoothness  of  surface  has  been  thus  obtained,  the 
final  polishing  should  be  given  first  with  a  stiff  brush-wheel  (Fig.  217a), 
used  with  the  pumice  stone,  and  then  with  moistened  whiting,  or  pre- 
cipitated French  chalk;  and  this  should, be  followed  with  a  soft  brush- 


277 


nq.2/7. 


2/8 

wheel  (Fig.  217b)  and  whiting^  and  finally  with  a  cotton  "buff"  wheel 
(Fig.  217c)  until  a  highly  polished  and  mirror-like  surface  presents. 

Such  a  finish  requires  but  little  effort  and  but  a  few  moments'  time 
and  is  always  indicated  because  of  the  more  artistic  appearance  of  the 
work,  and  of  its  being  thus  rendered  more  hygienic.  The  more  highly 
the  surfaces  of  metal  are  polished,  the  less  susceptible  are  they  to  dis- 
coloration, and  the  more  permanent  and  self-cleansing  is  the  finish,  be- 
cause less  opportunity  is  thus  afforded  for  the  subsequent  attachment  of 
accumulations  in  the  mouth. 

Jewelers'  rouge  and  various  other  polishing  compounds  are  often 
advocated  and  are  employed  with  the  "buff"  wheel  for  the  final  polishing, 
but  nothing  seems   to  produce  better  results  than   whiting,  if   properly 


Fi'cj.  218. 


used,  as  indicated  ;  and  the  reddish  color  imparted  by  rouge  to  the  metal, 
together  with  the  discoloration  of  the  fingers  incident  to  its  use,  are  more 
or  less  objectionable. 

As  single  crowns,  and  particularly  those  of  the 
Tacilitatins  Procedure,     "shell  or  telescope"  variety,  are  somewhat  difficult  to 
handle  while  polishing,  various    styles    of    "crown- 
holders"  have  been  devised  for  facilitating  this  part  of  the  work. 

The  most  ingenious  and  perhaps  universally  useful  of  these  instru- 
ments is  the  one  known  as  Fahey's  Ideal  Crown  Holder,  manufactured 
by  the  Dental  Specialties  Company,  of  Chicago  (Fig.  218).  This  is  adapt- 
able to  almost  any  size  of  crown,  because  of  one  blade  being  removable  ; 


279 

and,  the  spring  being  adjustable,  it  holds  the  crown  securely  with  little  or 
no  danger  of  distorting  its  shape. 

A  similar  device  which  is  also  useful  for  this  purpose  is  known  as 
the  "Burgess"  crown  holders,  and  is  shown  in  hig.  2iy. 

The  filling  of  the  crown  with  compounds  of  sealing  wax,  and  then 
inserting  a  piece  of  wood  into  it  while  it  is  hot,  is  sometimes  recom- 
mended, but  is  objectionable  because  of  the  difficulty  of  removing  the 
compound  after  the  polishing  is  completed  ;  and  the  fitting  of  the  end  of 
a  piece  of  wood  of  suitable  length  to  the  interior  of  the  crown  is  likewise 
a  poor  method,  because  of  the  possible  distortion  of  the  shape  of  the  band 
in  so  doing. 

While  dowel  crowns  are  not  quite  so  difficult  to  handle  in  the  polish- 
ing, the  use  of  one  of  the  pin  vises  previously  recommended  may  some- 
times be  found  convenient. 

Although  it  is  scarcely  possible  to  give  too  high 

Precautions.  a  polish  to  the  exposed  surfaces  of  metal  which  are 

to  be  permanently  fixed  in  the  mouth,  it  is,  however, 
quite  possible,  and  indeed  sometimes  quite  easy,  to  polish  through  the 
thinner  portions  of  a  crown  in  the  use  of  disks  and  felt  wheels ;  hence, 
in  polishing,  extreme  care  should  be  exercised  to  prevent  such  a  mishap, 
as  well  as  to  preclude  any  unnecessary  thinning  of  such  parts. 

6oia  Platittd. 

An  increased  artistic  effect,  and  a  more  permanent  finish,  may  be 
obtained  by  subjecting  the  piece  to  the  electroplating  process,  after  it  has 
been  highly  polished.  This  imparts  a  uniform  rich  yellow  color  to  all 
metal  surfaces  and  affords  a  surface  of  pure  gold  which  is  more  or  less 
permanent,  and  which  is  not  so  easily  attacked  and  discolored  by  the 
chemical  action  of  the  secretions. 

Solutions  for  this  purpose  may  be  made  by  dis- 
gyatUdC  Solution.  solving  fifteen  grains  of  the  chloride  of  gold  in  a 
porcelain  or  glass  vessel  containing  about  four 
ounces  of  distilled  water,  and  then  adding  to  this  a  like  quantity  of  water 
into  which  about  thirty  or  forty  grains  of  pulverized  potassium  cyanide 
has  also  been  previously  dissolved  in  a  similar  vessel.  This  is  known  as 
the  "cyanide  solution,"  the  approximate  formula  for  which,  as  generally 
employed,  is  as  follows  : 

Chloride  of  gold  gr.     xv. 

Cyanide  of  potassium      gr.  xxx.  to  xl. 
Distilled  water  oz.  viii. 

A  small  ordinary  "primary"  or  "dry  cell"  battery  may  be  used,  and 
the  work  to  be  plated  should  be  attached  to  the  negative  pole  and  then 


28o 

suspended  in  the  solution,  with  a  piece  of  thin  pure  gold  plate  likewise- 
suspended  from  the  positive  pole,  avoiding  contact  between  the  two. 

If  the  piece  is  zvell  finished  and  highly  polished,  and  then  washed 
with  bicarbonate  of  sodium  to  remove  all  traces  of  organic  matter,  and' 
then  fastened  to  the  pole  by  so  coiling  the  wire  as  to  have  a  well-distrib- 
uted contact  over  the  surface  of  the  metal  to  be  plated,  a  few  minutes' 
immersion  in  the  solution  will  afford  the  desired  result,  after  which  it. 
should  be  again  highly  polished  with  the  "hiiff"  wheel. 

Solutions  which  may  be  used  without  a  battery 
Prepared  Solutions,     are  prepared  for  this  purpose,  and  while  they  seenr 
to  afford  good  results,  the  deposit  of  gold  is  prob- 
ably not  so  heavy,  and  hence  not  so  permanent,  and  the  solution  can  only 
be  used  until  it  becomes  inactive. 

In  their  use  a  sufficient  quanity  of  the  solution  should  be  placed  ixt 
a  porcelain  or  glass  vessel  and  heated  until  ■ivarin,  and  the  work  then  at- 
tached to  a  strip  of  pure  zinc  and  immersed  therein. 

Moderate  heat  and  slight  agitation  will  effect  the  desired  result  in  a 
few  moments,  and  the  permanency  and  effectiveness  of  the  solution  may 
be  increased  by  suspending  a  small  piece  of  pure  gold  plate  on  another 
zinc  strip  hooked  over  the  edge  of  the  vessel  so  that  the  gold  is  immersed. 

mountifld 

No  portion  of  the  entire  procedure  incident  to  the  construction  and 
application  of  the  work  is  of  more  importance  than  the  detail  involved 
in  its  secure  and  permanent  attachment  to  the  root. 

In  order  that  such  a  fixation  may  be  secured  with  reasonable  facility, 
the  medium  used  must  possess  sufficient  plasticity  to  admit  of  the  proper 
and  accurate  adjustment  of  the  crown,  and  to  completely  fill  the  interven- 
ing space  between  it  and  the  root,  and  must  then  afford  a  substantial  and 
more  or  less  insoluble  and  impervious  union  between  the  two. 

Previous     to     any     effort     toward     permanent 

mnminary  mounting,  the  crown  should  ahvays  be  adjusted  to- 

>iaiu$Tment.  .  .  ,  /  .  .         . , 

position  on  the  root,  as  a  means  of  ascertaimng  with 

absolute  certainty  that  it  meets  with  all  the  requirements  of  fit,  occlu- 
.sion,  etc.,  as  well  as  to  admit  of  making  any  changes  in  its  form  or  shape 
which  may  be  necessary,  and  of  subsequently  repolishing,  which  cart 
never  be  done  so  well  after  permanent  fixation  is  secured. 

The  adjustment  may  be  greatly  facilitated  in  so  far  as  discomfiture 
to  the  patient  is  concerned  by  slightly  moistening  the  interior  of  the  band 
with  95  per  cent  carbolic  acid,  or  by  carefully  bathing  the  gum  surround- 
ing the  root  with  a  two  or  a  four  per  cent  solution  of  cocaine  just  pre- 
vious to  inserting  the  crown. 


28  I 

The  former  procedure  is  jxrhaps  the  more  simple,  equally  effective 
and  less  dangerous  one.  and  usually  affords  sufficient  anesthesia  of  the 
parts  to  admit  of  the  subsequent  permanent  mounting  without  any  ap- 
precialjle  discomtiture ;  and  any  possible  injury  to  the  tissues  from  the 
escharotic  effect  may  be  overcome  by  bathing  them  with  alcohol  as  soon  as 
the  crown  is  forced  to  place. 

The  driving  of  the  crown  to  position  is  never  warrantable  or  neces- 
sary if  the  adaptation  is  anywhere  near  correct;  anterior  crowns  can 
usually  be  forced  to  place  with  the  fingers,  and  a  firm  closure  of  the  jaw 
will  aid  in  adjusting  those  on  the  posterior  teeth.  In  the  event  of  the 
absence  of  occluding  teeth,  a  small  flat  piece  of  wood  may  be  used  to 
advantage  here,  as  indicated  in  the  fitting  of  bands. 

When  it  has  been  observed  that  the  adaptation  is  correct,  the  crown 
should  be  then  removed  and  mounted,  as  the  patient  should  never  be  dis- 
missed, no  matter  hotv  firm  it  may  remain  in  place  at  first,  without  the 
presence  of  some  medium  of  attachment  which  may  preclude  its  becom- 
ing loosened,  and  any  possible  distortion  of  the  fit  or  shape  which  might 
result  therefrom  in  wearing,  not  overlooking  the  danger  of  swallowing  it. 

Ccmporarv  mounting. 

In  the  event  of  permanent  mounting  being  contraindicated  for  a 
time,  the  crown  may  be  temporarily  mounted  in  a  manner  which  will  ad- 
mit of  its  being  worn  without  danger  of  becoming  loosened  or  distorted  in 
shape,  and  of  its  being  removed  with  facility  whenever  necessary. 

When  such  a  procedure  may  for  any  reason  be  indicated,  temporary 
stopping  will  serve  as  a  sufficiently  substantial  medium  to  afford  attach- 
ment from  sitting  to  sitting,  or  for  a  few  days'  duration,  but  it  does  not 
possess  sufficient  integrity  to  be  reliable  for  any  great  length  of  time. 

In  its  use,  the  root  should  be  dried  with  alcohol  and  hot  air,  and  a 
sufficient  quantity  thoroughly  heated  and  placed  inside  of  the  band,  and 
the  crown  then  quickly  forced  to  place,  after  which  it  may  be  chilled  with 
a  spray  of  cold  water  directed  upon  the  crown,  and  the  surplus  then 
trimmed  away. 

Crowns  so  mounted  may  be  easily  removed  with  a  pointed  instru- 
ment, hooked  over  the  edge  of  the  band,  as  heat  higher  than  the  temper- 
ature of  the  body  is  scarcely  ever  necessary  to  destroy  or  reduce  the  ad- 
hesive property  of  this  material,  which  accounts  for  its  not  being  reliable 
for  more  permanent  usage. 

Permanent  mountind. 

The  requirements  of  a  permanent  mounting  are  best  obtained  at  the 
present  time  in  the  use  of  the  oxyphosphate  of  zinc  cements  and  gutta 


282 

percha.  Amalgam  was  formerly  used  to  some  extent  but  has  been  prac- 
tically abandoned  in  view  of  the  greater  facility  with  which  either  of  these 
may  be  successfully  employed,  and  the  absence  of  adhesive  properties. 


Use  of  Cement 

Cement  is  perhaps  the  more  generally  employed  because  of  the  facility 
with  which  it  may  be  manipulated,  combined  with  its  adhesive  properties 
and  inherent  strength  when  moisture  is  excluded. 


Fi<j.220, 


The  disadvantages  incident  to  its  use  are  the  temporary  irritation  to 
the  tissues  in  mounting ;  the  possible  m*ore  or  less  permanent  irritation 
which  may  be  induced  by  hidden  particles  accidentally  left  in  contact 
with  the  gum  after  motinting;  its  susceptibility  to  dissolution  when  ex- 
posed to  the  action  of  the  secretions ;  its  possible  shrinkage  in  crystallizing, 
and  the  extreme  difficulty  with  which  a  crown  may  be  removed,  and  par- 
ticularly a  dowel   crown,  when   occasion  demands. 


283 

When  it  has  been  ascertained  that  the  adapta- 
Proccdurc.  tion  is  correct,  and  when  the  crown  is  ready  to  be 

permanentl}'   mounted,    its   inner    surface    should    l)e 
cleansed  with  alcohol,  and  thorouj^hly  dried   with  hot  air. 

The  root  should  now  be  rendered  aseptic  by  a  careful  bathing  with 
carbolic  acid,  or  by  the  use  of  pyrozone  or  hydrogen  peroxide,  or  any 
good  antiseptic,  and  then  thoroughly  dried  with  pledgets  of  cotton. 

Thorough  drying  is  absolutely  essential  and  may  be  facilitated  by 
precluding  contact  of  the  lips,  cheeks,  or  tongue,  with  cotton  rolls  or  pads, 
and  then  using  alcohol  or  chloroform  evaporated  with  compressed  air,  or 
warm  air  from  the  chip  blower.     The  non-absorbent  cotton  rolls  prepared 


/^y.  ee/. 


in  various  sizes  and  lengths  by  Johnson  and  Johnson  are  very  convenient 
for  such  purposes.  The  use  of  these  in  the  anterior  part  of  the  mouth 
is  illustrated  in  Fig.  220,  and  if  the  root  is  in  the  posterior  part  of  the 
mouth,  a  "mouth  prop"  adjusted  in  the  opposite  side  to  hold  the  mouth 
open  will  often  be  found  very  useful,  and  the  cotton  rolls  may  be  efifec- 
tively  retained  with  a  clamp  adjusted  to  an  adjacent  tooth.     Fig.  221. 

A  good  reliable  medium  setting  cement  should  now  be  mixed  to  a 
•creamy  consistency,  which  should,  and  can  best,  be  done  by  an  assistant, 
when  possible,  in  order  that  the  operator  may  confine  himself  to  observing 
that  the  root  does  not  become  moistened. 


284 

If  the  crown  possesses  a  dowel,  the  canal,  or 
Dowel  Crowns..  canals,  should  first  be  thoroughly  filled  with  the 
cement.  This  may  be  accomplished  by  using  a  root 
canal  plugger  and  a  pumping  action,  until  the  cement  has  been  carried  to 
the  extreme  ends.  A  cement  syringe  for  this  purpose  has  been  devised 
by  Dr.  H.  L.  Cruttenden,  but  its  use  usually  involves  more  time  than  is 
necessary  or  warrantable  for  such  a  simple  procedure. 

When  the  canal  has  been  thus  well  filled,  the  dowel  and  interior  of 
the  cap  should  be  coated  or  covered  with  a  layer  of  cement,  which,  if 
done  by  the  assistant  during  the  filling  of  the  canal,  will  greatly  expedite 
the  operation,  and  the  crown  should  then  be  quickly  and  firmly  pressed 
to  its  proper  position  on  the  root. 

After  becoming  assured  of  its  having  assumed  the  proper  relation, 
the  patient  may  be  requested  to  close  the  mouth  until  the  cement  has  at 
least  partially  crystallized,  the  length  of  time  required  for  which  will  be 
indicated  by  the  surplus  remaining  upon  the  mixing  slab.  It  is  desir- 
able that  the  first  stages  of  the  setting  of  the  cement  should  be  obtained 
under  pressure.  Therefore  the  operator  should  press  firmly  upon  the 
crown  with  the  finger  or  a  piece  of  soft  wood  for  at  least  five  minutes. 

The  crystallization   may  be  hastened  somewhat  by  directing  warm 
air  from  the  chip  blower  upon  the  crown,  and  when  sufficiently  hard,  all 
surplus  should  be  carefully  removed  with  pledgets  of  cotton,  and  a  sharp- 
pointed  explorer  passed  carefully  around  the  band  beneath  the  gum. 

A  ligature  drawn  through  the  interproximal  space  may  further  in- 
sure the  removal  of  any  remaining  surplus  at  these  points,  which  precau- 
tions are  always  advisable,  because  of  the  extreme  irritation  to  the  gum 
which  is  produced  by  such  hidden  particles  after  their  complete  crystalli- 
zation. 

Coating  the  outside  of  the  band  along  the  cervix  with  vaseline  or  oil 
just  previous  to  mounting  is  recommended  as  a  means  of  facilitating  the 
removal  of  the  excess  by  preventing  its  adhering  to  the  edge  or  surface  of 
the  crown. 

In  mounting  the  "shell  or  telescope"  crown,  the 
"Shell  or  same  detail  is  indicated,  but  as  a  larger  quantity  of 

telescope"  Crowns,    cement  must  be  placed  in  the  crown,  care  should  be 
exercised  to  have  it  cover  all  surfaces,  and  be  devoid 
of  air  spaces,  in  order  to  insure  the  complete  filling  of  the  entire  interven- 
ing space  between  it  and  the  root.     The  proper  quantity  is  governed,  of 
course,  by  the  length  of  the  root  which  projects  or  extends  into  the  crown. 

As  soon  as  the  crown  is  forced  to  place,  the  mouth  should  be  imme- 
diately closed  and  the  occlusion  observed,  and  when  this  is  as  it  should 
be,  which  will  be  indicated  by  the  normal  contact  of  the  adjacent  oppos- 


^85 

ing  natural  teeth,  a  roll  of  cotton  should  be  placed  between  the  crown 
and  the  opposing  teeth,  and  a  steady  and  firm  pressure  of  the  jaw  in 
normal  occlusion  maintained  until  the  cement  has  crystallized,  in  order  to 
prevent  any  possible  displacement. 

The  same  precautions  incident  to  the  removal  of  all  excess  cement 
should  then  be  observed  with  equal  rare,  and  before  dismissing  the  patient 
it  should  be  carefully  and  finally  noted  that  the  crown  does  not  occlude 
too  hard,  as  subsequent  discomfiture  will  invariably  result  if  this  con- 
dition exists. 

If  any  doubt  exists  as  to  the  accuracy  of  the  re- 
Tnturing  JlCCUracv  of    lation  of  the  cervical  edge  of  the  crown  to  the  per- 
Jldaptati^n  to  Root,     iphery  of  the  root,  some  means  of  insuring  a  close 
joint  between  them  should  be  observed. 
This  may  often  be  aided  materially  by  slightly  reducing  the  circum- 
ference of  the  edge  of  the  band  with  curved  or  small,  pointed  pliers,  just 


previous  to  the  final  mounting,  as  it  may  have  become  somewhat  en- 
larged, by  stretching,  in  the  fitting  and  preliminary  trials. 

The  use  of  a  smooth  foot  plugger  adjusted  to  the  automatic  mallet 
may  also  be  found  useful,  and  particularly  along  the  buccal  edge,  after 
the  crown  has  been  mounted ;  and  the  approximal  edges  may  be  brought 
into  closer  contact  by  inserting  a  small  amalgam  burnisher  into  the  inter- 
proximal spaces,  and  exerting  some  little  effort  in  this  direction.  Either 
a  suitable  burnisher,  such  as  is  illustrated  in  Fig.  222,  or  the  foot-plugger^ 
may  often  be  employed  to  good  advantage  upon  the  lingual  surface,  but 
in  the  use  of  either,  some  little  care  should  be  observed  to  avoid  produc- 
ing sharp  angles  at  the  corners,  and  yet  to  secure  a  close  adaptation  and 
particularly  at  the  bifurcation  of  the  roots. 

In  extreme  cases  of  ill  adaptation  or  of  exceedingly  constricted 
necks,  a  good  result  may  often  be  obtained  by  encircling  the  crown  with 
a  piece  of  German  silver,  or  copper  wire,  from  24  to  26  gauge,  passed 
through  the  interproximal  spaces,  and  the  ends  then  twisted  from  the 


286 

buccal  side  (Fig.  223),  until  the  loop  breaks.  This  affords  a  uniform 
compression  of  the  edge  of  the  band  by  condensing  the  molecules,  but 
in  effecting  it,  it  should  be  observed  that  the  wire  does  not  slip  beneath 
the  edge  of  the  band,  which  tendency  may  be  overcome  by  slightly  flatten- 
ing that  portior  which  rests  against  the  lingual  surface  of  the  crown,  or 
which  forms  the  center  of  the  loop.  While  ordinary  silver  suture  wire, 
or  .that  made  from  other  alloys  or  metals  may  be  used,  those  recommended 
give  the  best  results   because  of  their  tensile  strength. 

Wherever  possible,  all  of  these  procedures  should  be  observed,  or 
executed,  after  the  crown  has  been  properly  mounted,  and  a  firm  closure 
of  the  jaw  should  be  maintained,  in  order  to  prevent  lifting  it  from  its 


f/^.223. 


proper  relation.  The  cement  should  first  be  allowed  to  become  partially 
crystallized,  also,  in  order  that  any  slight  hemorrhage  produced  may  in- 
terfere as  little  as  possible  with  its  perfect  crystallization. 

An  instrument  designed  for  compressing  the  edge  of  the  band  after 
mounting  has  been  devised  by  Dr.  Rudolph  Beck,  of  Chicago  (Fig.  224,), 
and  may  sometimes  be  found  more  or  less  useful  for  this  purpose. 

When  two  or  more  crowns  are  to  be  inserted  at 

two  or  more  Crowns,    the  same  sitting,  each  should  be  mounted  separately, 

as  the  crystallization  of  the  cement   seldom  affords 

opportunity  for  the  thorough  and  accurate  mounting  of  more  than  one 


28; 

with  each  mixing;  and  the  operator  should  never  he  hurried,  nor  make 
any  effort  to  expedite  matters  to  too  great  an  extent  in  this  procedure. 

In  cases  of  extreme  pain  after  mounting,  which 
therapeutics.  is  sometimes  induced  by  the  irritating  influence  of 
tlie  cement  upon  inflamed  or  liypersensitive  tissues, 
but  which  is  usually  only  temporary,  relief  may  be  afforded  by  painting 
the  gums  around  the  neck  of  the  crown  with  a  two  or  a  four  per 
cent  solution  of  cocaine ;  or  with  the  tincture  of  iodine,  or  the  usual  rem- 
edies for  counter-irritation.  A  spray  of  hot  water  is  also  sometimes  very 
effective,  and  where  an  astringent  may  be  indicated,  in  cases  of  conges- 
tion, zinc  sulphate  or  a  saturated  solution  of  tannic  acid  in  glycerine  may 
be  employed. 

Use  or  Gutta  Percba. 

The  difficulty  encountered  in  the  removal  of  crowns  mounted  with 
cement,  and  particularly  of  dowel  crowns,  has  created  a  demand  for  some 


medium  which  would  afford  a  secure  and  reliable  attachment,  and  which 
would  at  the  same  time  admit  of  subsequent  removal  in  the  event  of 
necessity,  without  requiring  the  destruction  of  the  crown  or  of  any  ap- 
preciable amount  of  tooth  structure. 

The   ordinary    red    or    pink    base-plate    gutta 

JVdpantases.  percha,    skilfully   manipulated,    seems   to    meet    such 

requirements  in  admitting  of  easy  removal,  as  well 
as  to  possess  the  additional  desirable  qualities  of  offering  sufficient  in- 
tegrity in  the  attachment,  and  of  being  insoluble,  non-irritating,  and  more 
or  less  impervious. 

Its  use  also  affords  a  somewhat  cushion-like  seat  for  the  crown, 
which  is  an  advantage  because  of  relieving  the  "deadened  blow"  in  the 
stress  of  mastication,  and  of  thus  reducing  the  shock,  and  diminishing 
the  tendency  of  porcelain  to  fracture,  as  compared  with  a  more  non- 
yielding  medium. 


The   disadvantages  incident  to  the  employment 

Disadvantages.  of  this  material  lie  mainly  in  the  skill  and  time  re- 
quired to  successfully  manipulate  so  refractory  or  in- 
tractable a  substance ;  and  yet  its  integrity  as  a  substantial  mounting  is  due 
to  such  properties,  and  will,  of  course,  increase  in  proportion  thereto,  so 
long  as  it  is  capable  of  being  rendered  sufficiently  plastic  to  be  properly 
moulded,  in  the  adjustment  of  the  crown. 

While  its  employment  is  probably  more  especially  indicated  for  dowel 
crowns,  this  same  essential  property  may  here  prove  a  disadvantage,  if 
any  great  surplus  is  present,  by  offering  sufficient  resistance  to  expand 
the  band,  and  thus  destroy  the  accuracy  of  its  adaptation. 

This  objection  may  be  overcome,  however,  by  careful  manipulation 
in  obtaining  the  maximum  of  plasticity,  and  avoiding  the  presence  of  any 
unnecessary  surplus.  Successful  results  will  depend  upon  a  willingness 
to  consume  time,  and  to  observe  the  detail  with  deliberate  painstaking 
care,  as  well  as  in  the  acquirement  of  the  necessary  degree  of  skill;  and 
will  increase  in  proportion  thereto. 

In  its  manipulation,  the  material  should  be  cut 
Procedure.  into  narrow  shreds  or  strips,  from  one-half  to  one 

inch  in  length,  and  these  should  then  be  slowly  and 
carefully  heated  until  plastic.  The  heating  should  be  done  at  the  chair, 
and  may  be  best  accomplished  by  placing  them  on  a  porcelain-lined 
electric  gold  annealer,  such  as  is  manufactured  by  Mr.  M.  M. 
Kerr,  of  Detroit,  Mich. ;  or  upon  a  mica  slab  placed  over  a  flame,  where 
they  should  remain  until  the  mounting  is  completed.  The  Custer  electric 
gold  annealer  has  an  accompanying  porcelain  slab  which  may  also  be  used 
for  this  purpose. 

Direct  contact  with  the  flame  should  always  be  avoided,  as  this  de- 
stroys the  working  properties  of  the  material  by  rendering  it  harsh  and 
tough. 

While  the   gutta   percha   is   being  thus  heated. 

Dowel  Crowns.        the  dowel  of  the  crown  should    be    spurred  with  a 

sharp  knife-blade,  and  it  and  the  interior  of  the  cap 

then  slightly  moistened  with  a  solvent  of  gutta  percha,  to  facilitate  a 

secure  attachment.     Oil  of  cajeput  is  probably  the  best  solvent  for  this 

purpose,  though  oil  of  eucalyptol  or  chloroform  may  be  used. 

When  thus  prepared,  a  piece  of  the  gutta  percha  shotild  be  picked 
up  with  foil  carriers,  coiled  around  the  dowel  from  its  apex  downward. 
Fig.  225 A,  and  then  packed  down  closely  with  tlie  fingers.  If  one  piece 
does  not  appear  to  be  sufficient  for  the  first  trial,  another  may  be  added, 
tmtil  what  seems  to  be  adequate  is  obtained,  but  a  surplus  should  be 
avoided. 


289 

The  crown  should  now  be  placed  upon  the  heater,  and  the  canal  and 
end  of  the  root  then  moistened  with  a  spray  of  water  from  a  syrmge,  m 
order  to  prevent  the  gutta  percha  from  adhering,  after  which  the  heated 
crown  may  be  grasped  with  a  napkin  and  forced  to  position.  If  no  great 
surplus  has  been  used,  it  will  go  readily  to  place  without  driving,  when 
it  should  be  at  once  removed,  and  small  pieces  of  the  heated  material 
added,  where  needed;  it  is  then  placed  again  upon  the  heater,  the  root 
moistened,  and  this  procedure  continued  until  the  gutta  percha  is  moulded 
to  fill  the  space  between  crown  and  root,  when  the  correct  relation  exists. 

All  surplus  should  now  be  trimmed  off  even  with  the  edge  of  the 
band,  and  the  crown  then  replaced  upon  the  heater. 

In  the  event  of  the  presence  of  too  much  gutta  percha  to  admit  of  the 
proper  adjustment,  the  surplus  should  be  trimmed  away  with  a  hot  m- 
strument,  and  the  crown  reheated  and  carried  to  place,  until  the  proper 
.relation  maintains. 

The  procedure  indicated  in  the  mounting  of  the 

Shell  or  "shell    or    telescope"  crown  is  the  same,  except  that 

telescope  Crowns,      the  gutta  percha  may  be  cut  into  small  square  pieces, 

of  convenient  size ;  and  these  should  be  placed  in  the 


bottom  of  the  crown  and  around  the  joint  between  cusp  and  band,  until 
they  may  be  gradually  moulded  to  fill  the  space. 

Up  to  this  point,  the  root  should  be  moistened 
Tfnal  mounting.        previous  to  each  application  or  trial  of  either  style 
of  crown,   in  order  that  its   removal   may  be  made 
•easy  by  preventing  adhesion. 

When  ready  for  the  final  mounting,  the  crown  should  be  again 
placed  upon  the  heater,  and  allowed  to  remain  until  the  root  has  been 
rendered  aseptic,  and  then  thoroughly  dried  in  the  manner  indicated  in 
■connection  with  cement.  It  should  now  be  moistened  with  the  oil  of 
cajeput,  or  with  a  thin  solution  of  chloropercha,  and  the  crown  then 
picked  up  with  the  napkin,  and  forced  to  place,  where  it  should  be  held 
.firmly  for  a  few  moments,  until  the  gutta  percha  loses  its  heat,  which 
may  be  hastened  by  a  spray  of  cold  water. 


290 

£otnbinin9  Cement  and  Qutta  PercDa. 

While  either  cement  or  gutta  percha  may  be  used  in  mounting  shelf 
or  telescope  crowns,  on  the  posterior  teeth,  the  advantages  of  both  may 
be  obtained  for  dowel  crowns  by  combining  them.  This  may  be  done  in 
such  manner  as  to  admit  of  the  subsequent  removal  of  the  dowel,  in  case 
of  accident  or  necessity  without  any  great  difficulty,  and  to  overcome  any 
possible  danger  of  enlarging  the  narrow  band,  such  as  may  possibly  result 
from  the  use  of  gutta  percha  alone. 

Whatever  advantages  cement  may  possess  as  a  mounting  medium, 
it  is  seldom  the  best  practice  to  surround  the  dozvel  exclusively  with  this 
material,  because  of  the  extreme  difficulty  of  ever  removing  it  from  the 
root.  Hence,  if  one  is  not  sufficiently  skilled  in  the  manipulation  of  gutta. 
percha  alone,  some  means  of  facilitating  the  removal  of  such  crowns,. 
without  injury  to  the  root,  is  always  indicated. 

This    may   be   accomplished  by  using  sufficient. 

Procedure.  gutta  percha,  in  the  manner  described,  to  surround 

the    dowel   only    (Fig.   225B)    and   then   completing' 

the  mounting  by  filling  the  cap  and  coating  the  walls  of  the  canal  with 

cement,  thus  obtaining,  in  a  measure,  the  advantages  of  both,  with  lb" 

minimum  of  the  objections  of  each. 

Various  combination  cements  in  w4iich  gutta  percha  filings,  or  gutta 
percha  in  solution,  is  incorporated  with  the  oxy-phosphate  of  zinc,  are 
advocated,  but  as  their  use  is  at  present  somewhat  experimental  they  are 
not  recommended. 

Uariations  of  Proceaure. 

The  skill  required  to  successfully  manipulate  gutta  percha  has 
caused  the  adoption  of  several  variations  of  procedure,  each  with  a  view 
of  accomplishing  the  desired  result  with  greater  facility  and  expediency. 

A  thick  solution  of  gutta  percha  in  chloroform 
Use  ©f  0Woropcrcba,  is  sometimes  employed  for  the  entire  mounting  of 
dowel  crowns,  but  is  not  recommended,  because  of 
the  shrinkage  of  such  medium,  due  to  the  evaporation  of  the  chloroform. 
This  shrinkage  will,  of  course,  afford  some  opportunity  for  the  subsequent 
loosening  of  the  crown,  and  thus  diminshes  the  stability  and  permanency 
of  the  attachment. 

It  may  be  used  around  the  dowel  and  on  the  inner  surface  of  the  cap,, 
however,  in  place  of  the  base-plate  gutta  percha,  and  when  so  employed,, 
the  chloroform  should  first  be  evaporated  by  passing  over  a  flame,  and- 
the  crown  then  mounted  with  cement,  as  indicated.  This  prevents  the 
adhesion  of  the  cement  to  the  surfaces  of  the  dowel  and  cap,  which,  of; 


29.1 

course,  facilitates  the  removal  of  the  crown,  but  not  to  the  extent  afforded 
by  the  use  of  the  gutta  percha  alone,  when  it  entirely  fills  the  canal. 

A  heavy  coating  of  very  thick  shellac  or  sand- 
U$C  Of  Shellac         arac  varnish  over  the  dowel,  and  on  the  inside  of  the 
or  Sandarac.  cap  will  also  prevent  the  adhesion  of  the  cement  to 

the  metal,  and  thus  facilitate  the  removal  of  the 
crown,  and  particularly  of  the  dowel ;  and  while  it  is  better  to  use  either 
one  of  these  alcoholic  solutions  than  nothing  at  all,  their  similar  employ- 
ment only  affords  the  same  advantages  and  limitations  mentioned  in  con- 
nection with  the  use  of  chloropercha. 

A   preparation   of  rubber  in   the   form   of  very 
Rubber  tissue.         thin  tissue,  which  is  quite  adhesive,  is  recommended 
for  similar  use  by  Dr.  W.  F.  Lawrenz,  of  St.  Louis, 
but  at  the  present  stage  of  its  experimental  application,  it  seems  to  offer 
no  particular  advantages  over  the  preceding  materials,  and  is  more  diffi- 
cult to  manipulate. 

Tina!  Precautions. 

When  the  mounting  has  been  completed  with  apparent  satisfaction, 
the  patient  should  never  be  dismissed  until  it  has  been  carefully  ascer- 
tained that  the  crown  is  firm,  and  that  the  occlusion  and  all  surrounding 
conditions  are  favorable;  and  a  further  precaution  against  any  possiblo 
subsequent  displacement,  annoyance  or  discomfiture  should  be  observed 
by  requiring  the  patient  to  return  in  the  course  of  a  few  days  for  final 
inspection. 

Keitio<)ind  Crowns  mountca  witb  Gutta  Pcrcba. 

The  removal  of  crowns  mounted  with  gutta  percha  may  be 
easily  effected  by  applying  sufficient  heat  to  the  exposed  portion  of 
the  crown  to  soften  the  material.  This  may  be  done  by  heating  the 
beaks  of  a  pair  of  heavy  pliers  of  good  size,  placing  them  on  the  crown, 
and  sustaining  the  contact  until  the  heat  is  conveyed  throughout  its  length, 
which  will  usually  be  noted  by  a  response  from  the  patient,  when  the 
gutta  percha  surrounding  it  will  be  sufficiently  softened  to  lose  some  of 
its  adhesive  properties,  and  admit  of  the  ready  detachment  of  the  crown 
with  a  hooked  or  pointed  instrument. 

In  this  procedure,  care  should  be  exercised  to  guard  the  face  and 
lips  of  the  patient,  as  well  as  to  protect  the  porcelain,  which  may  be  aided 
by  cotton  rolls  or  pads ;  and  the  pliers  should  be  heated  in  the  laboratory, 
or  where  the  heating  may  not  be  observed  by  the  patient,  and  then  car- 
ried to  the  chair  wrapped  in  a  napkin  or  towel,  with  only  the  beaks  ex- 


292 

posed,  as  a  matter  of  convenience  to  the  operator,  and  of  protection  and 
relief  from  fear  to  the  patient. 

A  more  convenient  method  which  may  sometimes  be  employed  with 
success  has  been  suggested  by  Dr.  C.  B.  Rohland.  This  consists  in  plac- 
ing a  leather  or  moose-hide  polishing  wheel  in  the  engine  and  revolving 
it  with  rapidity  against  the  crown  until  the  friction  will  thus  produce 
sufficient  heat  to  admit  of  its  removal. 


INDEX 


Abrasion,    l-.xtensive,    liiy. 

Acid  Bath,   ;.'4. 

Accuracy    of    iVdaptation    Without   Band,    203. 

Accurate   I'ltting   JJowels,   '^2'J. 

Adaptation   of   lacings,    I4S. 

Adapting   Backing,   I'S:',. 

Facing,    \S:i. 
Adhesive   Wax,   :i\). 
Adjusting  Cusp,   'Jo. 
Adjustment  of   Dowel,    lyi. 
Alignment,   14il. 
Alloying,   IJ. 
Alloys,  10,   Hi. 

Uorrance's,    ID. 

Tusiblc,  :?ll. 

of  Gold,  10. 
Amalgam,   Application  of,  117. 
Anatomical   Relations,   48. 
Anterior    Crowns,    :i;iti,    231. 

Anterior   Teeth,   Applications   to  the,   118,   129. 
jVpplication  of  Amalgam,   117. 

Davis    Crown,   242. 

Detachable    and    Replaceable    Facings,    159. 

F'acings  to   Bicuspid   Crowns,   lo2. 

Partial   Bands,    155. 

Removable   Crowns,   171. 

Riveted    Facings,    15(1 

Saddle-]?ack    Teeth    to    Bicuspid    and    :\[olar 
Crowns,    130. 
Application    of   the    [ntradental   Band,    173. 

Logan,    Crown. 

to  Deciduous  Teeth,  124. 

Individual    Roots,   117. 

Irregularities,    131,    171. 

Separated  Molar  Roots,  115. 

the  Anterior  Teeth,  118,  129. 
Apposition,   27. 
Approximal  Contact,  49. 
Articulation   and   Oci;lusion,   49. 
Articulators,    Improved,    187. 
Artificial    Teeth,    Insertion   of    Gold   Fillings   in, 

269. 
Ash's  Crown   Swaging  Device,   05. 
Autogeneous  Soldering,   35. 

Backing,   130. 

Adapting,   1  33. 

in   Combination   V.'ith,   272. 

of    j'acing,    149. 

Rei)lacenient   of    Facing  and,    183. 

Soldering,    133. 
Baird    System,   102,   123. 
Bake,   l-'inal,   259. 

Primary,  259. 
"Balling  Up,"  27. 
Band,   130. 

Accuracy   of   Adaptation   Without,    202. 

and   Ca].,   With,   201.    207. 

and   Dowel,   With,   227. 

and  Dowel   Crown,   Preparation   for,   02,138. 


Band,    .application    of   the    Inlradenlal,    173. 

Preserving   Continuity   of,   127. 

Primary,    105. 

With,    lis,    2  43. 

Without,    lis,    244. 
Bands,  7'J,   110,  227. 

^Application    of    Partial,    155. 

Partial,  237. 
Base   Metals,   11,   29. 
Bicuspid    Crowns,    Application    of    Facings    to, 

132. 
Bite,   14S. 

and    Impressions,    100,    107,    229. 

Occluding,   84. 
Blanks.   113. 

Forming,   109. 
Block  Teeth,    Soldering,    29. 
Blowpipe,     Oxy-IIydrogen.     33. 
Bodies,    J'oundation   and    Enamel,    259. 

Gum    Jinamel,    250. 

High   and    Low    Fusing,    249. 
Body,    Manipulation   of,    253. 

^iixing,   254. 

One  Grade  of,  255. 
Borax,  20. 
Box  Method,   104. 
Brass,  1 9. 

Brewer's   Method,  177. 
Brewster    Crown,   213. 
Bridges,   Cantilever,   117. 
Brown   Crown,  the,  S. 
Bryant's   Method,   164,   181. 
Biittner  Crown,   0. 

Canals,  Preparation  of,   69. 
Cantilever   IJridges,    117. 
Cap,   Re-enforced,   107,   235. 

Separating   Dowel  and,  184. 

With    Hand   and,   201,   207. 
Caries,   Extensive,    46. 

Carved  Cusp  and  Special   Die  Methods,  88. 
Carving   and   Swaging,   122. 
Casting  Flasks,    107. 
Cements,   262,   289. 
Cervical   Curvature,   140. 

End,   14  9. 
Chloropercha,   290. 
Cigrand's   Method,    175. 
Coin  Gold.  16. 
Color,   141. 

and  Harmony,  141. 

Oil,   141,   256. 

Selection  of,  254. 
Coloring  Matter,  248. 
Compounding    Solders,    10. 
Composition     Characteristics    and     Manipulation 

of  Porcelain  Bodies,  247. 
Consideration    of   the   Metals,    15. 
Contouring,    82. 

and   Carving,   257. 


Cooling  After   Soldering,    34. 
<Jrown   Slitting   Forceps,    126. 
Curvature,    cervical,    ]  40. 
Cusp,   Adjusting,   93. 

Formation,    l-'rocesses   for,    87. 

J'ormation  Without  Models,  95. 

Soldering,    93. 

Solid    Cast,    94. 
Cusps,    116,    168. 
Cyanide  Solution,   279. 

Davis  and  Logan   Crowns,   Use  of  the,   241. 

Davis   Crown,   A])plication  of  the,   242. 

Davis  Crowns,  166. 

Deciduous   Teeth,   Application  to,   124. 

Development   of   Crown   Work,   History   and,   1. 

Devitalization,    Feasibility  of,   54. 

Die  and  Die-Plate  Methods,   97. 

I'late   Methods,    97,    122. 
Die-Plates,   97. 
Dies,  91,  108,   193. 

Individual,  97. 
Diminution    of    Normal    Space,    172. 
Dorrance  s   Alloy,   19. 
Dowel,   Adjustment   of,    191. 

and  Plate,  68,  236. 

Crown,    Preparation    for    Band   and,    02. 

Crown,    the   Band   and,    188. 

Crown  Without  Band,  Preparation  for,  67. 

Crowns,    188,    196,    2S.S,    288. 

Separating  Cap   and,    184. 

With   Band   and,   227. 
Dowels,  49,   124,   137,   140,   1S8,   193,  229. 

Accurate    Fitting,    229. 

Inseparable,   67,   199. 

Separable,  68,  199. 

Substituting    Separate,    210. 

Use  of  Two,    167. 
Drying  and   Pleating,   41 . 
Dwight's   Facing,   163,   179. 

Enamel  Cleavers,  Use  of,   64. 

Removal   of,    64. 
English   Tube   Teeth,   3. 
Esthetic    Relations,   50. 
Ivxcising  Bicuspids  and  Molars,  63. 

Forceps,   184. 

Jncisors  and  Cuspids,  63. 
Extension    for    Support   of    Facing,    172. 
Extensive  Abrasion,   129. 

Caries,    46. 

Pacing,  130,  168.  230. 

Adapting,  133. 

and    Backing,    Replacement   of,   183. 

]'>acking  of,    149. 

Dwight's,   163. 

Extension   for   Support   of,   172. 

Mason's,   160. 

Roach's.   161. 

Soldering.    134,    231. 

Use   of   Flat   Band,   168. 

Without,   234. 
Facings,  Adaptation  of,  148. 

Application  of  Riveted,  156. 

Application   of   Detachable  and   Replaceable, 
1  59. 

Replacement   of,  176. 

Replacing  Bicuspid  on    Molar,   182. 
l-'easibility  of  Devitalization,   54. 
Feldspar,   248. 
F'ellowship    Crown,    2  J  4. 
Finishing,    94,   115,   151,   155,   274. 
First    Application    of    Porcelain    Crowns,    2. 
Flame,  30. 

Flasks,   Casting,   107. 
Flux,  25,  248. 
Fluxed   Wax,    Parr's,   26. 
Foil  Gold,  270. 
Forceps,    Crown    Slitting,    126. 

Excising,    184. 
Forming   Blanks,   109. 


Foster    Crown,    4. 

Fractured  Roots,   Treatment  of,   71. 
Fracturing   of   Porcelain   F^acings,    28. 
Free   Exposure   of   the   Root,    56. 
Furnace  Heating,  262. 

Placing  Crown  in,  261. 

Supporting   Crown   in,   260. 
Furnaces,   265. 

Electric,  265. 

Gas,  269. 

Clasoline,   268. 
l^isible  Alloys,  20. 
Fusing,   262. 
I'using  Points,  251. 

Precautions  Incident  to,  260. 

Gates-Bonwill    Crown,    5. 
German    Silver,    20. 
Gold,   15. 

Alloys  of,   16. 

and    Platinum,    17. 

Coin,   16. 

Fillings    in    Artificial    Teeth,     Insertion     of, 
269. 

Foil,    270. 

Plating,   279. 

Platinized,   17. 

Pure,  263. 

Recovering  and  Refining  Waste,  22. 

Refining,    21. 

Roman,  271. 

Soldering,    33. 

Solders,    18. 
Gravity,    30. 
Gutta  Percha,   287,   289.   291. 

Hard  Wax,    39. 

Harmony,  141. 

Heat,    Uniform,    27. 

Hist9ry  and   Development  of  Crown  Work,    1. 

Hollingsworth    System,    99,   123. 

and  Baird  Systems,  123. 
Plow   Crown,   7. 
Howland-Perry  Crown,  5. 
Hygienic    Considerations,    172. 
Plypertrophy,  Treatment  of,   55. 

Imiiression,    85,    148. 

and   Bite,    106,   J  67,   229. 

of  Root,   193. 
Incisal  of  Occlusal  End,  149. 
In   Combination   With   Backing,   272. 
Indications   and    Requirements,    45. 

for   Porcelain  Jackets,   239. 
Individual    Dies,    97. 

Roots,   Application   to,   117. 
Inseparable    Dowels,    67,   199. 
Insertion    of    Gold    Fillings    in    Artificial    Teetli, 

269. 
Investing,    39,    153,    169. 

and   Investment  Materials,   36. 

Object   of,   36. 
Investment,  231. 

Preparation  of,   41. 

Preparing  Case  for.   38. 

Requirements   of   ar.,    38. 
Iridium,   16. 
Irregularities,    Application    to,    131,    171. 

Jacket  Crowns,  129,  238. 

Kaolin,  24  8. 
Karat,  15. 

Liquid  Soldering  Fluid,  26. 
Logan   Crown,   7,    203. 

Application  of  the,  244. 
Logan   Crowns,   Use  of  the  Da\ 
Dowry  System,   101,    123. 

and   Millett   Systems,    123. 

Mack  Crown,  4. 
Malformation,   47. 
Malformed   Teeth,    129. 


ind,   241. 


Alalposiliun,  iT,  171. 

Manipulation,   30. 

Mason  s  I'acing,   100. 

Metals,   Alloys   and   S.-ldcrs,    lu. 

Annealing  of,   13. 

J5ase,   '4\). 

Chemical  Action   oi,  i:i. 

C'liemical   and   I'hysical    I'roiicrucs   ut,    1-^. 

Color   of,    VJ. 

Consideration  of   the,    15. 

Ductility  of,  1~'. 

Fusibility    of,    1-'. 

MalleabilUy  of,    I  ;. 

Soldering  of,  13. 

Tempering  of,    13. 

Tenacity  of,   13. 

Welding    of,    13. 
Millett's    Systems,    IIIO,    1~'3. 
Mitchel's   Method,  ITS. 
Model   Making,  Accuracy  in,  18u. 
Model,    Swaging,    113. 
Models,  37. 

Preparing,    107. 
Molar   Koots,    Application   to    Separated,    115. 
JMould,   113.       • 
Mounting,   207^   274. 

Final,    289. 

Permanent,  281. 

Temporary,    281. 

Ivloble  and  Base   Methods,  11. 

•Object  of  investing,  3C. 
Occluding   Bite,    84. 
Occlusal   Ends,    Incisal  of.   149. 
Occlusion   and  Articulation,   49. 
Oxy-Hydrogen    Blowpipe,    33. 

Paralleling,  Converging  or  Diverging  Teeth,  GU. 

Parr's  Fluxed  Wax,  20. 

Partial   Bands,   237. 

Perforated    Roots,   Treatment   of,   70. 

Peripheral   Trimming,   (>5. 

Physiological    Considerations,    54. 

Relations,   48. 
Plate  and   Dowel,   (iS,  236. 
Platinized   Gold,   IT. 
Platinum,   15. 
Solder,   17. 
Soldering,  33. 
Use  of,   153. 
Polishing,  275,  276. 
Porcelain     Bodies,    Composition,    Characteristics 

and    Manipvilation   of,    247. 
Porcelain    Crowns,    221. 

Facings,    Fracturing   of,    28. 
Jackets,   Indications   for,   239. 
"the    Shell    or    Telescope    Crown    in    Combin- 
ation With,   128. 
Work,    213. 
Porosity,    264. 

Preparation    for   Band  and   Dowel   Crown,    62. 
for  Dowel  Crown  Without  Band,  67. 
for  Shell  or  Telescope  Crown,  57. 
for    Shell   or    Telescope    Crown    with    I'orce- 

lain  Facing,  62. 
of  Canals,   69. 
of  Investment,   41. 
of    Roots,    62. 
Prepared   Sokitions,   280. 
Preiiaring  Case  for   Investment,   38. 

Models,   107. 
Preserving   Continuity  of  Band,   127. 
Primary   Band,   1 05. 
Primitive   Application   of   Crowns,   2. 
Processes  for  Cusp    l''ormation,  87. 
Protection  of  Unsupported  Walls,  OS. 
Pure   flold   Soldering,    33. 

Ready-Made  r'Arms,  125, 

Recovering  and   Refining  Waste  Gold,  22. 

Rc--cnforccd    Caii,     107,   235. 


Kelining  Gold,   21. 

Relations,   Esthetic,   50. 

Removaoie   Crowns,   Application   to,  171. 

Removal  of  Enamel,  01. 

Removing  and   Repairing,    120,    175. 

Removing  Crowns  Mourned   with  Gutla   1  ercha. 

291. 
Removing    Wax,    40. 
Reijairing,   12T,    170,   201,J.15. 

and  Kemoving,  120,   IT^i. 
Replacement   of    1-acing  and    Packing,    183. 

of  hacings,  170. 
Replacing    Bicuspids   o'l    Molar    l-acing=,    1S2. 
Requirements  ot   an   Investment,  38. 
Riclimond   Crown,    0. 
Riveting,  158. 
Roach's  Facing,  101. 
Roman   Gold,    ..  I'l. 
Root,   Impression  of,   193. 
Preparation,   190,   227. 
Roots,    Preparation    of,    52. 
Rubber   Tissue,   290. 
Saddle-Back     Teeth     to      Bicuspid     and     Molar 

Crowns,    Application    of,    130. 
Sand    Bath,    24. 
Sandarac,    29<». 
Scott's   Method,   114. 
Seamless   Method,    m:;. 
SejjaraOle  Dowels,   08,   lO'.i. 
Separating  Cap  and  Dowel,  184. 
Separation  of    Teeth,  173. 
Shading,    X'ariations    in,    250. 
Shell   or   Telescope    Crown,   4,    T4,   284,   289. 

in    Combination    with   Porcelain,    128. 
Shellac,  29<i. 
Shrinkage,   28,   250. 
Silica,  -.^48. 
Silver  Solder,  20. 
Soft   Solder,  21. 
Soldering,  35. 
Solder,   Silver,  20. 

Soft,   21. 
Soldering,   23,   SO,   131,  151,  154,  109,  226. 
^Vutogeneous,   35. 
Backing,   133. 
Block  Teeth,  29. 
Cooling  After,   34. 
Cusp,   93. 
Facing,   134,  231. 
Fluid,   Li(|uid,   20. 
Gold,    33. 
Platinum,  33. 
Pure  Gold,   33. 
Soft,   35. 

With  Investment,  31. 
Without   Investment,   30. 
Solders,  10,   17. 

Compounding,   19. 
.Solid  Cast   Cusps,   94. 
Strength,  50. 
Stress,  48. 

Substituting   Separate    Dowels,   210. 
Swaging,    92,    110,    113. 
and  Carving,   122. 
Device,  Ash's  Crown,  95. 
Model,   113. 
Plate.  193. 
Sweating  Process,   34. 
System,    Baird,    102,    123. 
Hollingsworth,   99,  123. 
Lowry,   101,   123. 
Millett's,  100,  123. 
Telescope   Crown,   Preparation   for   Shell   or,   57. 
With     Porcelain      Facing,     Preparation     for 

Shell  or,   62. 
or   Shell    Crown.   •(,   74,   284,   289. 
or    Shell    Crown,    in    Combination   with    Por- 
celain,   128. 
Telescoping,  50. 
Tests,  203. 
Tem)iorary  Crowns,  217. 


Therapeutics,  53,  286. 

The   Shell  or  Telescope   Crown   in   Combination 

with    Porcelain,    128. 
To    Prevent   Unsoldering,   34. 
Treatment  of  Fractured  Koots,  71. 

of  Hypertrophy,   55. 

of  Perforated  Roots,   70. 
Trimming,  Peripheral,  65. 
Tube    Crowns,    216. 

Method,    166. 

Underwood's  Method,   178. 
Uniform  Heat,  27. 
Unsoldering,  to  Prevent,  34. 
Use  of  Enamel  Cleavers,  64. 
Flat-Back  Facing,  168. 


Platinum,   153. 

the    Davis    and   Logan    Crowns,    241. 

Two   Dowels,   167. 

Vulcanite  Teeth,  170. 

Wax,  Adhesive,  3'J. 

Hard,  39. 

Removing,  4  0. 
Webb  Crown,  8. 
Weston  Crown,  7. 
Williams's  Method,  174, 
With  Band,  118,  243. 

and  Cap,   201,   207. 

and  Dowel,  227. 
Without  Band,    118,  244. 

Facing,  231. 


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